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  • 1.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands;Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Alexander, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Bobulska, D.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Douglas, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Friday, D. A.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Grillo, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Longstaff, I.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    McHugh, N. T.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Petric, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Schiller, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Soler, F. J. P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Spradlin, P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Whitehead, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Search for the rare decays W+ →Ds+ ϒ and Z →D0 ϒ at LHCb2023Inngår i: Chinese Physics C, ISSN 1674-1137, E-ISSN 2058-6132, Vol. 47, nr 9, artikkel-id 093002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A search for the rare decays W+ -> D-s(+)gamma and Z -> D-0 gamma and is performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 2.0fb(-1). No significant signal is observed for either decay mode and upper limits on their branching fractions are set using W+ -> mu(+)nu and Z ->mu(+)mu(-)decays as normalization channels. The upper limits are and at 95% confidence level for W+ -> D-s(+)gamma and Z -> D-0 gamma the and decay modes, respectively. This is the first reported search for Z -> D-0 gamma the decay, while the upper limit on the Z -> D-0 gamma branching fraction improves upon the previous best limit.

  • 2.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands;Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Alexander, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Bobulska, D.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Douglas, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Friday, D. A.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Grillo, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Longstaff, I.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    McHugh, N. T.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Petric, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Schiller, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Soler, F. J. P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Spradlin, P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Whitehead, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Study of Bc+ meson decays to charmonia plus multihadron final states2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Four decay modes of the B-c(+) meson into a J/psi meson and multiple charged kaons or pions are studied using proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13TeV and corresponding to an integrated luminosity of 9 fb(-1). The decay B-c(+) -> J/psi K+ K- pi(+)pi(+)pi(-) is observed for the first time, and evidence for the B-c(+) -> J/psi 4 pi(+)3 pi(-) decay is found. The decay B-c(+) -> J/psi 3 pi(+)2 pi(-) is observed and the previous observation of the B-c(+) -> psi(2S)pi(+)pi(+)pi(-) decay is confirmed using the psi(2S) -> J/psi pi(+)pi(-) decay mode. Ratios of the branching fractions of these four B-c(+) decay channels are measured.

    Fulltekst (pdf)
    FULLTEXT01
  • 3. Aaij, R.
    et al.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    A study of CP violation in the decays B± → [K + K −π+π− ]D h± (h = K, π) and B± → [π+π−π+π− ]D h±2023Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, artikkel-id 547Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first study of CP violation in the decay mode B-+/- -> [K+K-pi(+)pi(-)](D)h(+/-), with h = K, pi, is presented, exploiting a data sample of proton-proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of 9fb(-1). The analysis is performed in bins of phase space, which are optimised for sensitivity to local CP asymmetries. CP-violating observables that are sensitive to the angle gamma of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for B-+/- -> [K+K-pi(+)pi(-)](D)h(+/-) and B-+/- -> [pi(+)pi(-)pi(+)pi(-)](D)h(+/-) decays.

    Fulltekst (pdf)
    fulltext
  • 4.
    Aaij, R.
    et al.
    Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Amplitude analysis of B0?: D0Ds+p - and B plus ? D -Ds plus p plus decays2023Inngår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, nr 1, artikkel-id 012017Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Resonant contributions in B0 & RARR; over bar D0D+s & pi;- and B+ & RARR; D-D+s & pi;+ decays are determined with an amplitude analysis, which is performed both separately and simultaneously, where in the latter case isospin symmetry between the decays is assumed. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. A doubly charged spin-0 open-charm tetraquark candidate together with a neutral partner, both with masses near 2.9 GeV, are observed in the Ds & pi; decay channel.

    Fulltekst (pdf)
    FULLTEXT01
  • 5.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands;Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Amplitude analysis of the D+s → π-π+π+ decay2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A Dalitz plot analysis of the D-s(+) -> pi(-)pi(+)pi(+) decay is presented. The analysis is based on proton-proton collision data recorded by the LHCb experiment at a centre-of-mass energy of 8TeV and corresponding to an integrated luminosity of 1.5 fb(-1). The resonant structure of the decay is obtained using a quasi-model-independent partial-wave analysis, in which the pi(+)pi(-) S-wave amplitude is parameterised as a generic complex function determined by a fit to the data. The S-wave component is found to be dominant, followed by the contribution from spin-2 resonances and a small contribution from spin-1 resonances. The latter includes the first observation of the D-s(+) -> omega(782)pi(+) channel in the D-s(+) -> pi(-)pi(+)pi(+) decay. The resonant structures of the D-s(+) -> pi(-)pi(+)pi(+) and D+ -> pi(-)pi(+)pi(+) decays are compared, providing information about the mechanisms for the hadron formation in these decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 6.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Zunica, G.
    Associated production of prompt J/ψ and (sic) mesons in pp collisions at √s=13 TeV2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 8, artikkel-id 93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The associated production of prompt J/psi and (sic) mesons in pp collisions at a centre-of-mass energy of root s = 13TeV is studied using LHCb data, corresponding to an integrated luminosity of 4 fb(-1). The measurement is performed for J/psi (sic) mesons with a transverse momentum pT < 10 (30) GeV/ c in the rapidity range 2.0 < y < 4.5. In this kinematic range, the cross-section of the associated production of prompt J/psi and (sic)(1S) mesons is measured to be 133 +/- 22 +/- 7 +/- 3 pb, with a significance of 7.9 s, and that of prompt J/psi and (sic)(2S) mesons to be 76 +/- 21 +/- 4 +/- 7 pb, with a significance of 4.9 sigma. The first uncertainty is statistical, the second systematic, and the third due to uncertainties on the used branching fractions. This is the first observation of the associated production of J/psi and (sic)(1S) in proton-proton collisions. Differential cross-sections are measured as functions of variables that are sensitive to kinematic correlations between the J/psi and (sic)(1S) mesons. The effective cross-sections of the associated production of prompt J/psi and (sic) mesons are obtained and found to be compatible with measurements using other particle productions.

    Fulltekst (pdf)
    FULLTEXT01
  • 7.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Associated production of prompt J/Ψ and Υ mesons in pp collisions at √ˆšs=13 TeV2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, artikkel-id 93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The associated production of prompt J/psi and (sic) mesons in pp collisions at a centre-of-mass energy of root s = 13TeV is studied using LHCb data, corresponding to an integrated luminosity of 4 fb(-1). The measurement is performed for J/psi (sic) mesons with a transverse momentum pT < 10 (30) GeV/ c in the rapidity range 2.0 < y < 4.5. In this kinematic range, the cross-section of the associated production of prompt J/psi and (sic)(1S) mesons is measured to be 133 +/- 22 +/- 7 +/- 3 pb, with a significance of 7.9 s, and that of prompt J/psi and (sic)(2S) mesons to be 76 +/- 21 +/- 4 +/- 7 pb, with a significance of 4.9 sigma. The first uncertainty is statistical, the second systematic, and the third due to uncertainties on the used branching fractions. This is the first observation of the associated production of J/psi and (sic)(1S) in proton-proton collisions. Differential cross-sections are measured as functions of variables that are sensitive to kinematic correlations between the J/psi and (sic)(1S) mesons. The effective cross-sections of the associated production of prompt J/psi and (sic) mesons are obtained and found to be compatible with measurements using other particle productions.

    Fulltekst (pdf)
    FULLTEXT01
  • 8.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Evidence for the decays B0 (*)0ϕ and updated measurements of the branching fractions of the Bs0 D(*)0ϕ decays2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 10, artikkel-id 123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Evidence for the decays B-0 -> (D) over bar (0)phi and B-0 -> (D) over bar (*0) phi is reported with a significance of 3.6 sigma and 4.3 sigma, respectively. The analysis employs pp collision data at centre-of-mass energies root s = 7, 8 and 13TeV collected by the LHCb detector and corresponding to an integrated luminosity of 9 fb(-1). The branching fractions are measured to be B(B-0 -> (D) over bar (0)phi) = (7.7 +/- 2.1 +/- 0.7 +/- 0.7) x 10(-7), B(B-0 -> (D) over bar (*0)phi) = (2.2 +/- 05 +/- 0.2 +/- 0.2) x 10(-6). In these results, the first uncertainty is statistical, the second systematic, and the third is related to the branching fraction of the B-0 -> (D) over bar K-0(+) K- decay, used for normalisation. By combining the branching fractions of the decays B-0 -> (D) over bar ((*)0)phi and B-0 -> (D) over bar ((*)0)omega, the omega-phi mixing angle delta is constrained to be tan(2)delta = (3.6 +/- 0.7 +/- 0.4) x 10(-3), where the first uncertainty is statistical and the second systematic. An updated measurement of the branching fractions of the B-s(0) -> (D) over bar ((*)0).phi decays, which can be used to determine the CKM angle gamma, leads to B(B-s(0) -> (D) over bar (0)phi) = (2.30 +/- 0.10 +/- 0.11 +/- 0.20) x 10(-5), B(B-s(0) -> (D) over bar (*0)phi) = (3.17 +/- 0.16 +/- 0.17 +/- 0.27) x 10(-5).

    Fulltekst (pdf)
    FULLTEXT01
  • 9.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Evidence of a J/ψK0S Structure in B0 → J/ψϕK0S Decays2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 13, artikkel-id 131901Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An amplitude analysis of B0 → J/ψϕK0S decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 9  fb−1, collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. Evidence with a significance of 4.0 standard deviations of a structure in the J/ψK0S system, named Tθψs1(4000)0, is seen, with its mass and width measured to be 3991+12−10+9−17  MeV/c2 and 105+29−25+17−23  MeV, respectively, where the first uncertainty is statistical and the second systematic. The Tθψs1(4000)0 state is likely to be the isospin partner of the Tθψs1(4000)+ state, previously observed in the J/ψK+ system of the B+ → J/ψϕK+ decay. When isospin symmetry for the charged and neutral Tθψs1(4000) states is assumed, the signal significance increases to 5.4 standard deviations.

    Fulltekst (pdf)
    FULLTEXT01
  • 10.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    First observation and branching fraction measurement of the Λb0 → Ds- p decay2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first observation of the Lambda(0)(b) -> D-s(-) p decay is presented using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of root s = 13TeV, corresponding to a total integrated luminosity of 6 fb(-1). Using the Lambda(0)(b) -> Lambda(+pi-)(c) decay as the normalisation mode, the branching fraction of the Lambda(0)(b) -> D-s(-) p decay is measured to be B (Lambda(0)(b) -> D-s(-) p) = (12.6 +/- 0.5 +/- 0.3 +/- 1.2) x 10(-6), where the first uncertainty is statistical, the second systematic and the third due to uncertainties in the branching fractions of the Lambda(0)(b) -> Lambda(+pi-)(c), D-s(-) -> K-K+pi(-) and Lambda(+)(c) -> pK(-)pi(+) decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 11.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    First observation and branching fraction measurement of the Λ›b0 →†’ Ds- p decay2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, artikkel-id 75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first observation of the Lambda(0)(b) -> D-s(-) p decay is presented using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of root s = 13TeV, corresponding to a total integrated luminosity of 6 fb(-1). Using the Lambda(0)(b) -> Lambda(+pi-)(c) decay as the normalisation mode, the branching fraction of the Lambda(0)(b) -> D-s(-) p decay is measured to be B (Lambda(0)(b) -> D-s(-) p) = (12.6 +/- 0.5 +/- 0.3 +/- 1.2) x 10(-6), where the first uncertainty is statistical, the second systematic and the third due to uncertainties in the branching fractions of the Lambda(0)(b) -> Lambda(+pi-)(c), D-s(-) -> K-K+pi(-) and Lambda(+)(c) -> pK(-)pi(+) decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 12.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subatom Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    First Observation of a Doubly Charged Tetraquark and Its Neutral Partner2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 4, artikkel-id 041902Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A combined amplitude analysis is performed for the decays B0-+ D0D thorn s & pi;- and B thorn -+ D-D thorn s & pi; thorn , which are related by isospin symmetry. The analysis is based on data collected by the LHCb detector in proton -proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. Two new resonant states with masses of 2.908 ⠂ 0.011 ⠂ 0.020 GeV and widths of 0.136 ⠂ 0.023 ⠂ 0.013 GeV are observed, which decay to D thorn s & pi; thorn and D thorn s & pi;- respectively. The former state indicates the first observation of a doubly charged open-charm tetraquark state with minimal quark content 1/2cs over bar ud over bar ⠃, and the latter state is a neutral tetraquark composed of 1/2cs over bar u over bar d ⠃ quarks. Both states are found to have spin-parity of 0 thorn , and their resonant parameters are consistent with each other, which suggests that they belong to an isospin triplet.

    Fulltekst (pdf)
    FULLTEXT01
  • 13.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Zunica, G.
    J/ψ and D0 production in √sNN=68.5GeV PbNe collisions2023Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, nr 7, artikkel-id 658Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The firstmeasurement of J/psi and D-0 production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/psi and D-0 mesons is studied with a beam of lead ions with an energy of 2.5 TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of root s(NN) = 68.5GeV. The J/psi/D-0 production crosssection ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from pNe collisions at the same energy and showno difference in the observed J/psi suppression trend when comparing pNe and PbNe peripheral collisions with PbNe central collisions.

    Fulltekst (pdf)
    FULLTEXT01
  • 14.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Measurement of CP asymmetries and branching fraction ratios of B- decays to two charm mesons2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 9, artikkel-id 202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The CP asymmetries of seven B- decays to two charm mesons are measured using data corresponding to an integrated luminosity of 9 fb(-1) of proton-proton collisions collected by the LHCb experiment. Decays involving a D*(0) or D-s(*-) meson are analysed by reconstructing only the D-0 or D-s(-) decay products. This paper presents the first measurement of A(CP) (B- -> D-s(*-) D-0) and A(CP) (B- -> D-s(-) D*(0)), and the most precise measurement of the other five CP asymmetries. There is no evidence of CP violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured.

    Fulltekst (pdf)
    FULLTEXT01
  • 15.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Zunica, G.
    Measurement of lepton universality parameters in B plus ?: K plus l + l - and B0? K?0l+l- decays2023Inngår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, nr 3, artikkel-id 032002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simultaneous analysis of the B thorn & RARR; K thorn e thorn e- and B0 & RARR; K & DBLBOND;0e thorn e- decays is performed to test muonelectron universality in two ranges of the square of the dilepton invariant mass, q2. The measurement uses a sample of beauty meson decays produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb-1. A sequence of multivariate selections and strict particle identification requirements produce a higher signal purity and a better statistical sensitivity per unit luminosity than previous LHCb lepton universality tests using the same decay modes. Residual backgrounds due to misidentified hadronic decays are studied using data and included in the fit model. Each of the four lepton universality measurements reported is either the first in the given q2 interval or supersedes previous LHCb measurements. The results are compatible with the predictions of the Standard Model.

    Fulltekst (pdf)
    FULLTEXT01
  • 16.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Measurement of (sic) production in pp collisions at √s=5 TeV2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 69Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The production cross-sections of (sic) mesons, namely (sic)(1S), (sic)(2S) and (sic)(3S), in pp collisions at root s = 5TeV are measured with a data sample corresponding to an integrated luminosity of 9.13 +/- 0.18 pb(-1) collected by the LHCb detector. The (sic) mesons are reconstructed in the decay mode (sic) -> mu(+)mu(-). Double differential cross-sections times branching fractions, as functions of the transverse momentum p(T) and the rapidity y of the (sic) mesons, are measured in the range pT < 20 GeV/ c and 2.0 < y < 4.5. The results integrated over these pT and y ranges are sigma((sic)(1S)) x B((sic)(1S) -> mu(+) mu(-)) = 2101 +/- 33 +/- 83 pb, sigma((sic)(2S)) x B((sic)(2S) -> mu(+) mu(-)) = 526 +/- 20 +/- 21 pb, sigma((sic)(3S)) x B((sic)(3S) -> mu(+) mu(-)) = 242 +/- 16 +/- 10 pb, where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different (sic) states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of (sic)(1S) at root s = 5TeV is updated as well using the directly measured cross-section results from this analysis.

    Fulltekst (pdf)
    FULLTEXT01
  • 17. Aaij, R.
    et al.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Zunica, G.
    Measurement of the Branching Fractions B(B0→p¯pp¯p) and B(B0s→p¯pp¯p)2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 9, artikkel-id 091901Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Searches for the rare hadronic decays B0→p¯pp¯p and B0s→p¯pp¯p are performed using proton-proton collision data recorded by the LHCb experiment and corresponding to an integrated luminosity of 9  fb−1. Significances of 9.3σ and 4.0σ, including statistical and systematic uncertainties, are obtained for the B0→p¯pp¯p and B0s→p¯pp¯p signals, respectively. The branching fractions are measured relative to the topologically similar normalization decays B0→J/ψ(→p¯p)K*0(→K+π−) and B0s→J/ψ(→p¯p)ϕ(→K+K−). The branching fractions are measured to be B(B0→p¯pp¯p)=(2.2±0.4±0.1±0.1)×10−8 and B(B0s→p¯pp¯p)=(2.3±1.0±0.2±0.1)×10−8. In these measurements, the first uncertainty is statistical, the second is systematic, and the third one is due to the external branching fraction of the normalization channel.

    Fulltekst (pdf)
    fulltext
  • 18.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, England.
    Measurement of the CKM angle γ using the B±→†’ D*h± channels2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 12, artikkel-id 013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A measurement of the CP-violating observables from B -> (DK +/-)-K-* and B-+/- -> D-*pi(+/-) decays is presented, where D-*(D) is an admixture of D-*0 and D-0 (D-0 and (0)) states and is reconstructed through the decay chains D-*-> D pi(0)/gamma and D -> KS0 pi+pi-/KS0K+K-. The measurement is performed by analysing the signal yield variation across the D decay phase space and is independent of any amplitude model. The data sample used was collected by the LHCb experiment in proton-proton collisions and corresponds to a total integrated luminosity of 9 fb(-1) at centre-of-mass energies of 7, 8 and 13 TeV. The CKM angle gamma is determined to be (69(-14)(+13))degrees using the measured CP-violating observables. The hadronic parameters r(B)(D)*(K +/-),r(B)(D)*(pi +/-),delta(D)(B)*(K +/-),delta(D)(B)*(pi +/-), which are the ratios and strong phase differences between favoured and suppressed B-+/- decays, are also reported.

    Fulltekst (pdf)
    FULLTEXT01
  • 19.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Measurement of the mass difference and relative production rate of the Ω−b and Ξ−b baryons2023Inngår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, nr 5, artikkel-id 052008Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mass difference between the Omega -b and Xi -b baryons is measured using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb-1, and is found to be mo Omega -bthorn - mo Xi -bthorn 1/4 248.54? 0.51ostatthorn ? 0.38osystthorn MeV=c2. The mass of the Omega -b baryon is measured to be mo Omega -bthorn 1/4 6045.9 ? 0.5ostatthorn ? 0.6osystthorn MeV=c2. This is the most precise determination of the Omega -b mass to date. In addition, the production rate of Omega -b baryons relative to that of Xi -b baryons is measured for the first time in pp collisions, using an LHCb dataset collected at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 6 fb-1. Reconstructing beauty baryons in the kinematic region 2 < <eta> < 6 and pT < 20 GeV=c with their decays to a J=psi meson and a hyperon, the ratio f Omega- b f Xi- b tation fractions of b quarks into Omega -b and Xi -b baryons, respectively, and B represents the branching fractions of their respective decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 20.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Measurement of the ratio of branching fractions B (B+cB0sπ+) /B (B+c →†’ J/ψπ+)2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 066Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ratio of branching fractions of B+cB0sπ+ and B+c J/ψπ+ decays is measured with proton-proton collision data of a centre-of-mass energy of 13TeV. The data were collected with the LHCb experiment during 2016-2018, corresponding to an integrated luminosity of 5.4 fb-1. The B0s mesons are reconstructed via the decays B0sJ/ψφ and B0sDsπ+. The ratio of branching fractions is measured to be B (B+cB0sπ+) /B (B+c →†’ J/ψπ+) = 91 ± 10 ± 8 ± 3 where the first uncertainty is statistical, the second is systematic and the third is due to the knowledge of the branching fractions of the intermediate state decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 21.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Measurement of the Ratios of Branching Fractions R(D*) and R(D0)2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 11, artikkel-id 111802Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ratios of branching fractions R(D*) = B((B) over bar -> D* tau(-) (v) over bar (tau))/B((B) over bar -> D*.mu(-)(v) over bar mu) and R(D-0) = B(B- -> D(0)t-mu(-)(v) over bar mu) are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb(-1) of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode tau(-) -> mu(-)v(tau)(v) over bar mu. The measured values are R(D) = 0.281 +/- 0.018 +/- 0.024 and R(D-0) = 0.441 +/- 0.060 +/- 0.066, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is rho = -0.43. The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard model.

    Fulltekst (pdf)
    FULLTEXT01
  • 22.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Measurement of the Time-Integrated CP Asymmetry in D0 → K-K+ Decays2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 9, artikkel-id 091802Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The time-integrated CP asymmetry in the Cabibbo suppressed decay PKK is measured using proton proton collision data, corresponding to an integrated luminosity of 5.7 th collected at a center of mass energy of 13 TeV with the LHCb detector. The D mesons are required to originate from promptly produced DD's decays, and the charge of the companion pion is used to determine the flavor of the charm meson at production. The time integrated CP asymmetry is measured to be Acr(KK) 6,815.41.6 x 10 where the first uncertainty is statistical and the second systematic. The direct CP asymmetries in D-K-K and D -> decays, and are derived by combining Ace(KK) with the time integrated CP asymmetry differ ence, AAcr-Acr(KK)-A(x), and other inputs, giving a (7.715.7) x 10, (23.2 16.1) x 10, with a correlation coefficient corresponding to p=0.88. The compatibility of these results with CP symmetry is 1.4 and 3.8 standard deviations for DKK and D degrees-xx decays, respectively. This is the first evidence for direct CP violation in a specific Do decay.

    Fulltekst (pdf)
    FULLTEXT01
  • 23.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Measurement of Υ production in pp collisions at √ˆšs=5 TeV2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, artikkel-id 69Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The production cross-sections of Υ mesons, namely Υ(1S), Υ(2S) anΥ(3S), in pp collisions at root s = 5TeV are measured with a data sample corresponding to an integrated luminosity of 9.13 +/- 0.18 pb(-1) collected by the LHCb detector. The (sic) mesons are reconstructed in the decay mode Υ -> mu(+)mu(-). Double differential cross-sections times branching fractions, as functions of the transverse momentum p(T) and the rapidity y of the (sic) mesons, are measured in the range pT < 20 GeV/ c and 2.0 < y < 4.5. The results integrated over these pT and y ranges are sigma(Υ(1S)) x B(Υ(1S) -> mu(+) mu(-)) = 2101 +/- 33 +/- 83 pb, sigma(Υ(2S)) x B(Υ(2S) -> mu(+) mu(-)) = 526 +/- 20 +/- 21 pb, sigma(Υ(3S)) x B(Υ(3S) -> mu(+) mu(-)) = 242 +/- 16 +/- 10 pb, where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different (sic) states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of Υ(1S) at root s = 5TeV is updated as well using the directly measured cross-section results from this analysis.

    Fulltekst (pdf)
    FULLTEXT01
  • 24. Aaij, R.
    et al.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Observation and branching fraction measurement of the decay Ξb → Λ0bπ−2023Inngår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, nr 7, artikkel-id 072002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The decay E-b -> A0bx-- is observed using a proton-proton collision data sample collected at center-of-ffiffimass energy p s 1/4 13 TeV with the LHCb detector, corresponding to an integrated luminosity of 5.5 fb-1. This process is mediated by the s -> uu over bar d quark-level transition, where the b quark in the E-b baryon is a spectator in the decay. Averaging the results obtained using the two A0b decay modes, A0b -> A thorn c x-- and A0b -> A thorn c x--x- thorn x--, the relative production ratio is measured to be ofE-b =fA0b thorn BoE-b -> A0bx-- thorn 1/4 o7.3 ⠂ 0.8 ⠂ 0.6 thorn x 10-4. Here the uncertainties are statistical and systematic, respectively, and fE-bofA0b thorn is the fragmentation fraction for a b quark into a E-b (A0b) baryon. Using an independent measurement of fE-b =fA0b, the branching fraction BoE-b -> A0bx-- thorn 1/4 o0.89 ⠂ 0.10 ⠂ 0.07 ⠂ 0.29 thorn % is obtained, where the last uncertainty is due to the assumed SU(3) flavor symmetry in the determination of fE-b =fA0b.

    Fulltekst (pdf)
    fulltext
  • 25.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subatom Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Observation of a J/ΨΛ Resonance Consistent with a Strange Pentaquark Candidate in B- →†’ J/ψΛ(p)over-bar Decays2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 3, artikkel-id 031901Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An amplitude analysis of B- -> J/psi Lambda(p) over bar decays is performed using 4400 signal candidates selected on a data sample of pp collisions recorded at center-of-mass energies of 7, 8, and 13 TeV with the LHCb detector, corresponding to an integrated luminosity of 9 fb(-1). A narrow resonance in the J/psi Lambda system, consistent with a pentaquark candidate with strangeness, is observed with high significance. The mass and the width of this new state are measured to be 4338.2 +/- 0.7 +/- 0.4 MeV and 7.0 +/- 1.2 +/- 1.3 MeV, where the first uncertainty is statistical and the second systematic. The spin is determined to be 1/2 and negative parity is preferred. Because of the small Q-value of the reaction, the most precise single measurement of the B- mass to date, 5279.44 +/- 0.05 +/- 0.07 MeV, is obtained.

    Fulltekst (pdf)
    FULLTEXT01
  • 26.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Observation of New Baryons in the Ξbπ+π and Ξ0bπ+π Systems2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 17, artikkel-id 171901Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first observation and study of two new baryonic structures in the final state Xi(0)(b)pi(+)pi(-) and the confirmation of the Xi(b)(6100)(-) state in the Xi(-)(b)pi(+)pi(-) decay mode are reported using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb(-1). In addition, the properties of the known Xi(b)*(0), Xi(b)'(-) and Xi(b)*(-) resonances are measured with improved precision. The new decay mode of the Xi(0)(b) baryon to the Xi(+)(c) pi(-) pi(+) pi(-) final state is observed and exploited for the first time in these measurements.

    Fulltekst (pdf)
    FULLTEXT01
  • 27.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Observation of New Ω0c States Decaying to the Ξ+cK Final State2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 13, artikkel-id 131902Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new excited states, Ωc(3185)0 and Ωc(3327)0, are observed in the Ξ+cK invariant-mass spectrum using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9  fb−1. Five previously observed excited Ω0c states are confirmed, namely Ωc(3000)0, Ωc(3050)0, Ωc(3065)0, Ωc(3090)0, and Ωc(3119)0. The masses and widths of these seven states are measured with the highest precision to date.

    Fulltekst (pdf)
    FULLTEXT01
  • 28.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands;Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Observation of the B0s → D*+ D*- decay2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first observation of the B-s(0) -> D*+ D*- decay and the measurement of its branching ratio relative to the B-0 -> D*+ D*(-) decay are presented. The data sample used corresponds to an integrated luminosity of 9 fb(-1) of proton-proton collisions recorded by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018. The decay is observed with more than 10 standard deviations and the time-integrated ratio of branching fractions is determined to be [GRAPHICS] . where the first uncertainty is statistical, the second systematic and the third due to the uncertainty of the fragmentation fraction ratio f(s)/f(d). The B-s(0) -> D*(+) D*(-) branching fraction is calculated to be [GRAPHICS] . where the fourth uncertainty is due to the B-0 -> D*(+) D*(-) branching fraction. These results are calculated using the average B-s(0) meson lifetime in simulation. Correction factors are reported for scenarios where either a purely heavy or a purely light B-s(0) eigenstate is considered.

    Fulltekst (pdf)
    FULLTEXT01
  • 29.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Observation of the B0s → χc1(3872)π+π- decay2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first observation of the B-s(0) -> (chi(c1)(3872) -> J/Psi pi(broken vertical bar) pi(-)) pi(broken vertical bar) pi(-) decay is reported using proton-proton collision data, corresponding to integrated luminosities of 1, 2 and 6 fb(-1), collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13TeV, respectively. The ratio of branching fractions relative to the B-s(0) -> (Psi(2S) -> J/Psi pi(+) pi(-)) pi(+) pi(-) decay is measured to be [GRAPHICS] where the first uncertainty is statistical and the second systematic. The mass spectrum of the pi(+) pi(-) system recoiling against the chi(c1)(3872) meson exhibits a large contribution from B-s(0) -> chi(c1)(3872) (integral(0)(980) -> pi(+) pi(-)) decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 30. Aaij, R.
    et al.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Observation of the decays B(s)0 →†’ Ds1(2536)∓ˆ“K±2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, artikkel-id 106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports the observation of the decays B-(s)(0) -> D-s1(2536)K--/+(+/-) using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb(-1). The branching fractions of these decays are measured relative to the normalisation channel B-0 -> (D) over bar (K+K-)-K-0. The D-s1(2536)(-) meson is reconstructed in the (D) over bar*(2007)K-0(-) decay channel and the products of branching fractions are measured to be B(B-s(0) -> D-s1(2536)K--/+(+/-)) x B(D-s1(2536)(-) -> D ($) over bar*(2007)K-0(-)) = (2.49 +/- 0.11 +/- 0.12 +/- 0.25 +/- 0.06) x 10(-5), B(B-0 -> D-s1(2536)K--/+(+/-) ) x B(D-s1(2536)(-) -> (D) over bar*(2007)K-0(-)) = (0.510 +/- 0.021 +/- 0.036 +/- 0.050) x 10(-5). The first uncertainty is statistical, the second systematic, and the third arises from the uncertainty of the branching fraction of the B-0 -> (D) over bar (K+K-)-K-0 normalisation channel. The last uncertainty in the B-s(0) result is due to the limited knowledge of the fragmentation fraction ratio, f(s)/f(d). The significance for the B-s(0) and B-0 signals is larger than 10 sigma. The ratio of the helicity amplitudes which governs the angular distribution of the D-s1(2536)(-) -> (D) over bar*(2007)K-0(-) decay is determined from the data. The ratio of the S- and D-wave amplitudes is found to be 1.11 +/- 0.15 +/- 0.06 and the phase difference between them 0.70 +/- 0.09 +/- 0.04 rad, where the first uncertainty is statistical and the second systematic.

    Fulltekst (pdf)
    FULLTEXT01
  • 31.
    Aaij, R.
    et al.
    Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Open charm production and asymmetry in pNe collisions at √sNN=68.5 GeV2023Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, artikkel-id 541Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A measurement of D-0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of D-0 mesons is studied with a beam of 2.5 TeV protons colliding on a gaseous neon target at rest, corresponding to a nucleon-nucleon centre-of-mass energy of root s(NN) = 68.5 GeV. The sum of the D-0 and (D-0) over bar production cross-section in pNe collisions in the centre-of-mass rapidity range y(star) is an element of[-2.29, 0] is found to be sigma(y star is an element of[-2.29, 0])(D0) = 48.2 +/- 0.3 +/- 4.5 mu b/nucleon where the first uncertainty is statistical and the second is systematic. The D-0 - (D-0) over bar production asymmetry is also evaluated and suggests a trend towards negative values at large negative y(star). The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1% intrinsic charm and 10% recombination contributions better describe the data than the other models considered.

    Fulltekst (pdf)
    FULLTEXT01
  • 32.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Precision Measurement of CP Violation in the Penguin-Mediated Decay B0s → ϕϕ2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 17, artikkel-id 171802Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A flavor-tagged time-dependent angular analysis of the decay B0s -> phi phi is performed using pp collision integrated luminosity of 6 fb-1. The CP-violating phase and direct CP-violation parameter are measured to s = -0.042 +/- 0.075 +/- 0.009 rad and l lambda l = 1.004 +/- 0.030 +/- 0.009, respectively, assuming the same values for all polarization states of the phi phi system. In these results, the first uncertainties are statistical and the second systematic. These parameters are also determined separately for each polarization state, showing no evidence for polarization dependence. The results are combined with previous LHCb measurements using pp collisions at center-of-mass energies of 7 and 8 TeV, yielding phi sss over bar s = -0.074 +/- 0.069 rad and l lambda l = 1.009 +/- 0.030. This is the most precise study of time-dependent CP violation in a penguindominated B meson decay. The results are consistent with CP symmetry and with the standard model predictions.

    Fulltekst (pdf)
    FULLTEXT01
  • 33.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Search for CP violation in D(s)+ → K- K+ K+ decays2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A search for direct CP violation in the Cabibbo-suppressed decay D-s(+) -> K-K+ K+ and in the doubly Cabibbo-suppressed decay D+ -> K- K+ K+ is reported. The analysis is performed with data collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of 13TeV corresponding to an integrated luminosity of 5.6 fb(-1). The search is conducted by comparing the D-(s)(+) and D-(s)(-) Dalitz-plot distributions through a model-independent binned technique, based on fits to the K-K+K+ invariantmass distributions, with a total of 0.97 (1.27) million D-s(+) (D+) signal candidates. The results are given as p-values for the hypothesis of CP conservation and are found to be 13.3% for the D+ -> K-K+ K+ decay and 31.6% for the D+ -> K-K+ K+ decay. No evidence for CP violation is observed in these decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 34.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Search for CP violation in the phase space of D0→ π-π+π0 decays with the energy test2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 9, artikkel-id 129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A search for CP violation in D-0 -> pi(-)pi(+)pi(0) decays is reported, using pp collision data collected by the LHCb experiment from 2015 to 2018 corresponding to an integrated luminosity of 6 fb(-1). An unbinned model-independent approach provides sensitivity to local CP violation within the two-dimensional phase space of the decay. The method is validated using the Cabibbo-favoured channel D-0 -> K-pi(+)pi(0) and background regions of the signal mode. The results are consistent with CP symmetry in this decay.

    Fulltekst (pdf)
    FULLTEXT01
  • 35.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands;Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Search for D* (2007)0 → μ+ μ- in B- → π- μ+ μ- decays2023Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, nr 7, artikkel-id 666Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The very rare D*(2007)0 → μ+ μ- decay is searched for by analysing B- → π- μ+ μ- decays. The analysis uses a sample of beautymesons produced in protonproton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb-1. The signal signature corresponds to simultaneous peaks in the μ+ μ- and π- μ+ μ- invariant masses. No evidence for an excess of events over background is observed and an upper limit is set on the branching fraction of the decay at B(D*(2007)0 → μ+ μ-) < 2.6 x 10-8 at 90% confidence level. This is the first limit on the branching fraction of D*(2007)0 -> → μ+ μ- decays and the most stringent limit on D* (2007)0 decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 36.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Study of the Bose-Einstein correlations of same-sign pions in proton-lead collisions2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 9, artikkel-id 172Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Correlations of same-sign charged pions are analysed using proton-lead collision data collected by the LHCb experiment at a nucleon-nucleon centre-of-mass energy of 5.02TeV, corresponding to an integrated luminosity of 1.06 nb(-1). Bose-Einstein correlations are observed in the form of an enhancement of pair production for same-sign charged pions with a small four-momentum difference. The dependence of the correlation radius and the intercept parameter on the reconstructed charged-particle multiplicity is investigated. The measured correlation radii scale linearly with the cube root of the reconstructed charged-particle multiplicity, being compatible with predictions of hydrodynamic models on the collision system evolution.

    Fulltekst (pdf)
    FULLTEXT01
  • 37.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Test of Lepton Universality in b→sℓ+ℓ− Decays2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 5, artikkel-id 051803Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first simultaneous test of muon-electron universality using B+→K+ℓ+ℓ− and B0→K*0ℓ+ℓ− decays is performed, in two ranges of the dilepton invariant-mass squared, q2. The analysis uses beauty mesons produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9  fb−1. Each of the four lepton universality measurements reported is either the first in the given q2 interval or supersedes previous LHCb measurements. The results are compatible with the predictions of the Standard Model.

    Fulltekst (pdf)
    FULLTEXT01
  • 38.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Zunica, G.
    Λc+ polarimetry using the dominant hadronic mode2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 228Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The polarimeter vector field for multibody decays of a spin-half baryon is introduced as a generalisation of the baryon asymmetry parameters. Using a recent amplitude analysis of the Lambda(+)(c) -> pK(-)pi(+) decay performed at the LHCb experiment, we compute the distribution of the kinematic-dependent polarimeter vector for this process in the space of Mandelstam variables to express the polarised decay rate in a model-agnostic form. The obtained representation can facilitate polarisation measurements of the Lambda(+)(c) baryon and eases inclusion of the Lambda(+)(c)-> pK(-)pi(+) decay mode in hadronic amplitude analyses.

    Fulltekst (pdf)
    FULLTEXT01
  • 39.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Adlarson, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Λc+ polarimetry using the dominant hadronic mode2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, artikkel-id 228Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The polarimeter vector field for multibody decays of a spin-half baryon is introduced as a generalisation of the baryon asymmetry parameters. Using a recent amplitude analysis of the Lambda(+)(c) -> pK(-)pi(+) decay performed at the LHCb experiment, we compute the distribution of the kinematic-dependent polarimeter vector for this process in the space of Mandelstam variables to express the polarised decay rate in a model-agnostic form. The obtained representation can facilitate polarisation measurements of the Lambda(+)(c) baryon and eases inclusion of the Lambda(+)(c)-> pK(-)pi(+) decay mode in hadronic amplitude analyses.

    Fulltekst (pdf)
    FULLTEXT01
  • 40.
    Aaij, R.
    et al.
    Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Alexander, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Bobulska, D.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Douglas, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Friday, D. A.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Grillo, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Longstaff, I.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    McHugh, N. T.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Petric, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Schiller, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Soler, F. J. P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Spradlin, P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Whitehead, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Model-independent measurement of charm mixing parameters in B → D0(→ K0Sπ+π- )ÎŒ-ΜΌX decays2023Inngår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, nr 5, artikkel-id 052005Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A measurement of charm mixing and CP-violating parameters is reported, using B over bar -> D0(-> K0S pi+pi-)x mu- nu over bar mu X decays reconstructed in proton-proton collisions collected by the LHCb experiment during the years 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb-1. The measured mixing and CP-violating parameters are xCP = [4.29 1 1.48(stat) 1 0.26(syst)] x 10-3, yCP = [12.61 1 3.12(stat) 1 0.83(syst)] x 10-3, Ax = [-0.77 1 0.93(stat) 1 0.28(syst)] x 10-3, Ay = [3.01 1 1.92(stat) 1 0.26(syst)] x 10-3. The results are complementary to and consistent with previous measurements. A combination with the recent LHCb analysis of D*+ -> D0(-> K0S pi+ pi-)pi+ decays is reported.

    Fulltekst (pdf)
    FULLTEXT01
  • 41.
    Aaij, R.
    et al.
    Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Alexander, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Bobulska, D.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Douglas, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Friday, D. A.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Grillo, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Longstaff, I.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    McHugh, N. T.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Petric, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Schiller, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Soler, F. J. P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Spradlin, P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Whitehead, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Study of charmonium decays to KS0Kπ in the B → (KS0Kπ)K channels2023Inngår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, nr 3, artikkel-id 032010Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A study of the B+ -> (KSK+)-K-0 K-pi(+) and B+ -> (KSK+K+)-K-0 pi(-) decays is performed using proton-proton collisions at center-of-mass energies of 7, 8 and 13 TeV at the LHCb experiment. The (KSK)-K-0 pi invariant mass spectra from both decay modes reveal a rich content of charmonium resonances. New precise measurements of the eta(c) and eta(c)(2S) resonance parameters are performed and branching fraction measurements are obtained for B+ decays to eta(c), J/psi, eta(c)(2S) and chi(c1) resonances. In particular, the first observation and branching fraction measurement of B+ -> chi K-c0(0)pi(+) is reported as well as first measurements of the B+ -> (KK+K-)-K-0 pi(+) and B+ -> (KK+K+)-K-0 pi(-) branching fractions. Dalitz plot analyses of eta(c) -> (KSK)-K-0 pi and eta(c)(2S) -> (KSK)-K-0 pi decays are performed. A new measurement of the amplitude and phase of the K pi S-wave as functions of the K pi mass is performed, together with measurements of the K-0*(1430), K-0*(1950) and a(0)(1700) parameters. Finally, the branching fractions of chi(c1) decays to K* resonances are also measured.

    Fulltekst (pdf)
    FULLTEXT01
  • 42.
    Aaij, R.
    et al.
    Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Alexander, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Bobulska, D.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Douglas, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Friday, D. A.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Grillo, L.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Longstaff, I.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    McHugh, N. T.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Petric, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Schiller, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Soler, F. J. P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Spradlin, P.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Whitehead, M.
    Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Study of the B- → Λc+(Λ)over-barc-K- decay2023Inngår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, nr 1, artikkel-id 012020Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The decay B- -> Lambda(+)(c)(Lambda) over bar K--(c)- is studied in proton-proton collisions at a center-of-mass energy of root s = 13 TeV using data corresponding to an integrated luminosity of 5 fb(-1) collected by the LHCb experiment. In the Lambda K-+(c)- system, the Xi(c)(2930)(0) state observed at the BABAR and Belle experiments is resolved into two narrower states, Xi(c)(2923)(0) and Xi(c)(2939)(0), whose masses and widths are measured to be m(Xi(c)(2930)(0) = 2924.5 +/- 0.4 +/- 1.1 Mev, m Xi(c)(2930)(0)) = 2938.5 +/- 0.9 +/- 2.3 Mev, Gamma(Xi(c)(2930)(0)) = 4.8 +/- 0.9 +/- 1.5 MeV, Gamma(Xi(c)(2930)(0) - 11.0 +/- 1.9 +/- 7.5 MeV, where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt Lambda K-+(c)- sample. Evidence of a new Xi(c)(2930)(0) state is found with a local significance of 3.8 sigma, whose mass and width are measured to be 2881.8 +/- 3.1 +/- 8.5 MeV and 12.4 +/- 5.3 +/- 5.8 MeV, respectively. In addition, evidence of a new decay mode Xi(c)(2930)(0) -> Lambda K-+(c) is found with a significance of 3.7 sigma. The relative branching fraction of B- -> Lambda(+)(c)(Lambda) over bar K--(c)- with respect to the B- -> D+D-K- decay is measured to be 2.36 +/- 0.11 +/- 0.22 +/- 0.25, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 43.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands;Tsinghua Univ, Ctr High Energy Phys, Beijing, Peoples R China.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Amplitude analysis of the D+-> pi(-)pi(+)pi(+) decay and measurement of the pi(-)pi(+) S-wave amplitude2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, artikkel-id 44Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An amplitude analysis of the D+-> (-)pi(+)pi(+) decay is performed with a sample corresponding to 1.5 fb(-1) of integrated luminosity of pp collisions at a centre-of-mass energy root s = 8 TeV collected by the LHCb detector in 2012. The sample contains approximately six hundred thousand candidates with a signal purity of 95%. The resonant structure is studied through a fit to the Dalitz plot where the pi(-)pi(+) S-wave amplitude is extracted as a function of pi(-)pi(+) mass, and spin-1 and spin-2 resonances are included coherently through an isobar model. The S-wave component is found to be dominant, followed by the rho(770)(0)pi(+) and f(2)(1270)pi(+) components. A small contribution from the omega(782) -> pi(-)pi(+) decay is seen for the first time in the D+-> pi(-)pi(+)pi(+) decay.

    Fulltekst (pdf)
    FULLTEXT01
  • 44.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands;Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, UK.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, UK.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Charmonium production in pNe collisions at √sNN = 68.5 GeV2023Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, nr 7, artikkel-id 625Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The measurement of charmonium states produced in proton-neon ( pNe) collisions by the LHCb experiment in its fixed-target configuration is presented. The production of J/ψ and ψ(2S) mesons is studied with a beam of 2.5 TeV protons colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy √sNN = 68.5 GeV. The data sample corresponds to an integrated luminosity of 21.7 ± 1.4 nb−1 . The J/ψ and ψ(2S) hadrons are reconstructed in μ+μ− final states. The J/ψ production cross-section per target nucleon in the centre-of-mass rapidity range y ∈ [−2.29, 0] is found to be 506 ± 8 ± 46 nb/nucleon. The ratio of J/ψ and D0 cross-sections is evaluated to (1.06 ± 0.02 ± 0.09)%. The ψ(2S) to J/ψ relative production rate is found to be (1.67 ± 0.27 ± 0.10)% in good agreement with other measurements involving beam and target nuclei of similar sizes.

    Fulltekst (pdf)
    FULLTEXT01
  • 45.
    Aaij, R.
    et al.
    Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    J/ψˆ and D0 production in âˆ√sNN=68.5GeV PbNe collisions2023Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, artikkel-id 658Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first measurement of J/psi and D-0 production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/psi and D-0 mesons is studied with a beam of lead ions with an energy of 2.5 TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of root s(NN) = 68.5GeV. The J/psi/D-0 production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from pNe collisions at the same energy and show no difference in the observed J/psi suppression trend when comparing pNe and PbNe peripheral collisions with PbNe central collisions.

    Fulltekst (pdf)
    FULLTEXT01
  • 46.
    Aaij, R.
    et al.
    Univ Groningen, Van Swinderen Inst, Groningen, Netherlands;Univ Maastricht, Maastricht, Netherlands.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Measurement of the CKM angle γ with B± → D[K∓π±π±π∓] h± decays using a binned phase-space approach2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, nr 7, artikkel-id 138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The CKM angle gamma is determined from CP-violating observables measured in B-+/- -> D[K--/+pi(+/-)pi(+/-)pi(-/+)]h(+/-), (h = K, pi) decays, where the measurements are performed in bins of the decay phase-space of the D meson. Using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13TeV, corresponding to a total integrated luminosity of 9 fb(-1), gamma is determined to be gamma = (54.8 (+6.0)(-5.8) (+0.6)(-0.6) (+6.7)(-4.3))degrees, where the first uncertainty is statistical, the second systematic and the third from the external inputs on the coherence factors and strong phases of the D-meson decays.

    Fulltekst (pdf)
    FULLTEXT01
  • 47.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands;Tsinghua Univ, Ctr High Energy Phys, Beijing, Peoples R China.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland..
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Measurement of the Z boson production cross-section in proton-lead collisions at root(NN)-N-s=8.16 TeV2023Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, artikkel-id 22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article presents the first measurement of the differential Z-boson production cross-section in the forward region using proton-lead collisions with the LHCb detector. The dataset was collected at a nucleon-nucleon centre-of-mass energy of root(NN)-N-s = 8.16TeV in 2016, corresponding to an integrated luminosity of 30.8 nb(-1). The forward-backward ratio and the nuclear modification factors are measured together with the differential crosssection as functions of the Z boson rapidity in the centre-of-mass frame, the transverse momentum of the Z boson and a geometric variable phi*. The results are in good agreement with the predictions from nuclear parton distribution functions, providing strong constraining power at small Bjorken-x.

    Fulltekst (pdf)
    FULLTEXT01
  • 48.
    Aaij, R.
    et al.
    Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Multidifferential study of identified charged hadron distributions in Z-tagged jets in proton-proton collisions at √s=13  TeV2023Inngår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, nr 3, artikkel-id L031103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a Z boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20<pT<100  GeV and in the pseudorapidity range 2.5<η<4. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64  fb−1. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.

    Fulltekst (pdf)
    FULLTEXT01
  • 49.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subat Phys, Amsterdam, Netherlands.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Institution School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Institution School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom.
    Zunica, G.
    Observation of a Resonant Structure near the D+sDs Threshold in the B+ → D+sDsK+ Decay2023Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 131, nr 7, artikkel-id 071901Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An amplitude analysis of the B+→D+sD−sK+ decay is carried out to study for the first time its intermediate resonant contributions, using proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. A near-threshold peaking structure, referred to as X(3960), is observed in the D+sD−s invariant-mass spectrum with significance greater than 12 standard deviations. The mass, width, and the quantum numbers of the structure are measured to be 3956±5±10  MeV, 43±13±8  MeV, and JPC=0++, respectively, where the first uncertainties are statistical and the second systematic. The properties of the new structure are consistent with recent theoretical predictions for a state composed of c¯cs¯s quarks. Evidence for an additional structure is found around 4140 MeV in the D+sD−s invariant mass, which might be caused either by a new resonance with the 0++ assignment or by a J/ψϕ↔D+sD−s coupled-channel effect.

    Fulltekst (pdf)
    FULLTEXT01
  • 50.
    Aaij, R.
    et al.
    Nikhef Natl Inst Subatom Phys, Amsterdam, Netherlands.
    Eklund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland.
    Kupsc, Andrzej
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik. Univ Glasgow, Sch Phys & Astron, Glasgow, Lanark, Scotland.
    Zunica, G.
    Univ Manchester, Dept Phys & Astron, Manchester, Lancs, England.
    Search for the baryon- and lepton-number violating decays B0 → pÎŒ- and Bs0 → pÎŒ-2023Inngår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, nr 1, artikkel-id 012021Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A search for the baryon- and lepton-number violating decays B-0 -> p mu(-) and B-s(0) -> p mu(-) is performed at the LHCb experiment using data collected in proton-proton collisions at root s = 7, 8 and 13 TeV, corresponding to integrated luminosities of 1, 2, and 6 fb(-1), respectively. No significant signal for B-0 -> p mu(-) and B-s(0) -> p mu(-) decays is found and the upper limits on the branching fractions are determined to be B(B-0 -> p mu(-)) < 2.6(3.1) x 10(-9) and B(B-s(0) -> p mu(-)) < 12.1(14.0) x 10(-9), respectively, at 90% (95%) confidence level. These are the first limits on these decays to date.

    Fulltekst (pdf)
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