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  • 301. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Measurement of B(s)(0) Mixing Parameters from the Flavor-Tagged Decay B(s)(0)-> J/psi phi2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 24, p. 241801-Article in journal (Refereed)
    Abstract [en]

    From an analysis of the flavor-tagged decay B(s)(0)-> J/psi phi we obtain the width difference between the B(s)(0) light and heavy mass eigenstates, Delta Gamma(s)=0.19 +/- 0.07(stat)(-0.01)(+0.02)(syst) ps(-1), and the CP-violating phase, phi(s)=-0.57(-0.30)(+0.24)(stat)(-0.02)(+0.08)(syst). The allowed 90% CL intervals of Delta Gamma(s) and phi(s) are 0.06 <Delta Gamma(s)< 0.30 ps(-1) and -1.20 <phi(s)< 0.06, respectively. The data sample corresponds to an integrated luminosity of 2.8 fb(-1) accumulated with the D0 detector at the Fermilab Tevatron collider.

  • 302. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Measurement of the Electron Charge Asymmetry in p(p)over-bar -> W plus X -> e nu plus X Events at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 21, p. 211801-Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the electron charge asymmetry in p (p) over bar -> W + X -> e nu + X events at a center of mass energy of 1.96 TeV using 0.75 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider. The asymmetry is measured as a function of the electron transverse momentum and pseudorapidity in the interval (-3.2, 3.2) and is compared with expectations from next-to-leading order calculations in perturbative quantum chromodynamics. These measurements will allow more accurate determinations of the proton parton distribution functions.

  • 303. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Measurement of the inclusive jet cross section in p(p)over-bar collisions at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 6, p. 062001-Article in journal (Refereed)
    Abstract [en]

    We report on a measurement of the inclusive jet cross section in p (p) over bar collisions at a center-of-mass energy root s = 1.96 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider corresponding to an integrated luminosity of 0: 70 fb(-1). The data cover jet transverse momenta from 50 to 600 GeV and jet rapidities in the range -2.4 to 2.4. Detailed studies of correlations between systematic uncertainties in transverse momentum and rapidity are presented, and the cross section measurements are found to be in good agreement with next-to-leading order QCD calculations.

  • 304. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Measurement of the Polarization of the Upsilon(1S) and Upsilon(2S) States in pp Collisions at s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 18, p. 182004-Article in journal (Refereed)
    Abstract [en]

    We present a study of the polarization of the Upsilon(1S) and Upsilon(2S) states using a 1.3 fb(-1) data sample collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron Collider. We measure the polarization parameter alpha=(sigma(T)-2 sigma(L))/(sigma(T)+2 sigma(L)), where sigma(T) and sigma(L) are the transversely and longitudinally polarized components of the production cross section, as a function of the transverse momentum (p(T)(Upsilon)) for the Upsilon(1S) and Upsilon(2S). Significant p(T)(Upsilon)-dependent longitudinal polarization is observed for the Upsilon(1S). A comparison with theoretical models is presented.

  • 305. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Observation of the B(c) meson in the exclusive decay B(c)-> J/psi pi2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 1, p. 012001-Article in journal (Refereed)
    Abstract [en]

    A fully reconstructed B(c)-> J/psi pi signal is observed with the D0 detector at the Fermilab Tevatron p (p) over bar collider using 1.3 fb(-1) of integrated luminosity. The signal consists of 54 +/- 12 candidates with a significance that exceeds 5 standard deviations, and confirms earlier observations of this decay. The measured mass of the B(c) meson is 6300 +/- 14(stat)+/- 5(syst) MeV/c(2).

  • 306. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Observation of the Doubly Strange b Baryon Omega(-)(b)2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 23, p. 232002-Article in journal (Refereed)
    Abstract [en]

    We report the observation of the doubly strange b baryon Omega(-)(b) in the decay channel Omega(-)(b) -> J/psi Omega(-), with J/psi -> mu(+)mu(-) and Omega(-) -> Lambda K(-) -> (p pi(-))K(-), in p (p) over bar collisions at root s = 1.96 TeV. Using approximately 1.3 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider, we observe 17.8 +/- 4.9(stat) +/- 0.8(syst) Omega(-)(b) signal events at a mass of 6.165 +/- 0.010(stat) +/- 0.013(syst) GeV. The significance of the observed signal is 5.4 sigma, corresponding to a probability of 6.7 x 10(-8) of it arising from a background fluctuation.

  • 307. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Observation of ZZ Production in p(p)over-bar Collisions at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 17, p. 171803-Article in journal (Refereed)
    Abstract [en]

    We present an observation for ZZ -> l(+) l(-) l'(+) l'(-) (l, l' =e or mu) production in p (p) over bar collisions at a center-of-mass energy of root s = 1.96 TeV. Using 1.7 fb(-1) of data collected by the D0 experiment at the Fermilab Tevatron Collider, we observe three candidate events with an expected background of 0.14(-0.02)(+0.03) events. The significance of this observation is 5.3 standard deviations. The combination of D0 results in this channel, as well as in ZZ -> l(+) l(-) v (v) over bar yields a significance of 5.7 standard deviations and a combined cross section of sigma(ZZ) = 1.60 +/- 0.63(stat)(-0.17)(+0.16)(syst) pb.

  • 308. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Precise Measurement of the Top-Quark Mass from lepton plus jets Events2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 18, p. 182001-Article in journal (Refereed)
    Abstract [en]

    We measure the mass of the top quark using top-quark pair candidate events in the lepton+jets channel from data corresponding to 1 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron collider. We use a likelihood technique that reduces the jet energy scale uncertainty by combining an in situ jet energy calibration with the independent constraint on the jet energy scale (JES) from the calibration derived using photon+jets and dijet samples. We find the mass of the top quark to be 171.5 +/- 1.8(stat.+JES)+/- 1.1(syst.) GeV.

  • 309. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for Anomalous Wtb Couplings in Single Top Quark Production2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 22, p. 221801-Article in journal (Refereed)
    Abstract [en]

    In 0.9 fb(-1) of pp collisions, the D0 Collaboration presented evidence for single top quark production in events with an isolated lepton, missing transverse momentum, and two to four jets. We examine these data to study the Lorentz structure of the Wtb coupling. The standard model predicts a left-handed vector coupling at the Wtb vertex. The most general lowest dimension, CP-conserving Lagrangian admits right-handed vector and left- or right-handed tensor couplings as well. We find that the data prefer the left-handed vector coupling and set upper limits on the anomalous couplings. These are the first direct constraints on a general Wtb interaction and the first direct limits on left- and right-handed tensor couplings.

  • 310. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et. al.,
    Search for Charged Higgs Bosons Decaying into Top and Bottom Quarks in pp Collisions2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 19, p. 191802-Article in journal (Refereed)
    Abstract [en]

    We describe a search for production of a charged Higgs boson, qq>-> H(+), reconstructed in the tb final state in the mass range 180 <= M(H)(+)<= 300 GeV. The search was undertaken at the Fermilab Tevatron collider with a center-of-mass energy s=1.96 TeV and uses 0.9 fb(-1) of data collected with the D0 detector. We find no evidence for charged Higgs boson production and set upper limits on the production cross section in the types I, II, and III two-Higgs-doublet models (2HDMs). An excluded region in the (M(H)(+), tan beta) plane for type I 2HDM is presented.

  • 311. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for decay of a fermiophobic Higgs boson h(f) -> gamma gamma with the D0 detector at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 5, p. 051801-Article in journal (Refereed)
    Abstract [en]

    We report the results of a search for a narrow resonance decaying into two photons in 1.1 fb(-1) of data collected by the D0 experiment at the Fermilab Tevatron Collider during the period 2002-2006. We find no evidence for such a resonance and set a lower limit on the mass of a fermiophobic Higgs boson of m(hf) > 100 GeV at the 95% C.L. This exclusion limit exceeds those obtained in previous searches at the Fermilab Tevatron and covers a significant region of the parameter space B(h(f) -> gamma gamma) vs m(hf) which was not accessible at the CERN Large Electron-Positron Collider.

  • 312. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for Higgs bosons decaying to tau pairs in p(p)over-bar collisions with the D0 detector2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 7, p. 071804-Article in journal (Refereed)
    Abstract [en]

    We present a search for the production of neutral Higgs bosons phi decaying into tau(+)tau(-) final states in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of approximately 1 fb(-1), were collected by the D0 experiment at the Fermilab Tevatron Collider. Limits on the production cross section times branching ratio are set. The results are interpreted in the minimal supersymmetric standard model yielding limits that are the most stringent to date at hadron colliders.

  • 313. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for large extra dimensions via single photon plus missing energy final states at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 1, p. 011601-Article in journal (Refereed)
    Abstract [en]

    We report on a search for large extra dimensions in a data sample of approximately 1 fb(-1) of p (p) over bar collisions at root s=1.96 TeV. We investigate Kaluza-Klein graviton production with a photon and missing transverse energy in the final state. At the 95% C.L. we set limits on the fundamental mass scale M(D) from 884 to 778 GeV for two to eight extra dimensions.

  • 314. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for long-lived particles decaying into electron or photon pairs with the D0 detector2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 11, p. 111802-Article in journal (Refereed)
    Abstract [en]

    In this Letter we report on a search for long-lived particles that decay into final states with two electrons or photons. Such long-lived particles arise in a variety of theoretical models, such as hidden valleys and supersymmetry with gauge-mediated breaking. By precisely reconstructing the direction of the electromagnetic shower we are able to probe much longer lifetimes than previously explored. We see no evidence of the existence of such long-lived particles and interpret this search as a quasi model-independent limit on their production cross section, as well as a limit on a long-lived fourth generation quark.

  • 315. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for Neutral Higgs Bosons in Multi-b-Jet Events in pp Collisions at s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 22, p. 221802-Article in journal (Refereed)
    Abstract [en]

    Data recorded by the D0 experiment at the Fermilab Tevatron Collider are analyzed to search for neutral Higgs bosons produced in association with b quarks. This production mode can be enhanced in the minimal supersymmetric standard model (MSSM). The search is performed in the three b quark channel using multijet triggered events corresponding to an integrated luminosity of 1 fb(-1). No statistically significant excess of events with respect to the predicted background is observed and limits are set in the MSSM parameter space.

  • 316. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for pair production of doubly charged Higgs bosons in the H(++)H(--)->mu(+)mu(+)mu(-)mu(-) final state2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 7, p. 071803-Article in journal (Refereed)
    Abstract [en]

    We report the results of a search for pair production of doubly charged Higgs bosons via p (p) over bar -> H(++)H(--)X ->mu(+)mu(+)mu(-)mu(-)X at root s=1.96 TeV. We use a data set corresponding to an integrated luminosity of 1.1 fb(-1) collected from 2002 to 2006 by the D0 detector at the Fermilab Tevatron Collider. In the absence of an excess above the standard model background, lower mass limits of M(H(L)(+/-+/-))> 150 GeV/c(2) and M(H(R)(+/-+/-))> 127 GeV/c(2) at 95% C.L. are set, respectively, for left-handed and right-handed doubly charged Higgs bosons assuming a 100% branching ratio into muons.

  • 317. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for the Standard Model Higgs Boson in the Missing Energy and Acoplanar b-Jet Topology at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 25, p. 251802-Article in journal (Refereed)
    Abstract [en]

    We report a search for the standard model Higgs boson in the missing energy and acoplanar b-jet topology, using an integrated luminosity of 0.93 fb(-1) recorded by the D0 detector at the Fermilab Tevatron p (p) over bar Collider. The analysis includes signal contributions from p (p) over bar -> ZH -> v (v) over barb (b) over bar, as well as from WH production in which the charged lepton from the W boson decay is undetected. Neural networks are used to separate signal from background. In the absence of a signal, we set limits on sigma(p (p) over bar -> VH) x B(H -> b (b) over bar) at the 95% C.L. of 2.6-2.3 pb, for Higgs boson masses in the range 105-135 GeV, where V W, Z. The corresponding expected limits range from 2.8 to 2.0 pb.

  • 318. Abazov, V. M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for Third Generation Scalar Leptoquarks Decaying into tau b2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 24, p. 241802-Article in journal (Refereed)
    Abstract [en]

    We have searched for third generation leptoquarks (LQ(3)) using 1.05 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider operating at s=1.96 TeV. We set a 95% C.L. lower limit of 210 GeV on the mass of a scalar LQ(3) state decaying solely to a b quark and a tau lepton.

  • 319. Abazov, V. M.
    et al.
    Strandberg, Jonas
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    et, al.
    Search for supersymmetry with gauge-mediated breaking in diphoton events at DØ2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 4Article in journal (Refereed)
    Abstract [en]

    We report the results of a search for supersymmetry (SUSY) with gauge-mediatedbreaking in the missing transverse energy distribution of inclusive diphoton events using 263 pb -1 of data collected by the DO experiment at the Fermilab Tevatron Collider in 2002-2004. No excess is observed above the background expected from standard model processes, and lower limits on the masses of the lightest neutralino and chargino of about 108 and 195 GeV, respectively, are set at the 95% confidence level. These are the most stringent limits to date for models with gauge-mediated SUSY breaking with a short-lived neutralino as the next-to-lightest SUSY particle. 

  • 320. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Direct Measurement of the Mass Difference between Top and Antitop Quarks2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 13, p. 132001-Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the mass difference between t and (t) over bar quarks in lepton + jets final states of t (t) over bar events in 1 fb(-1) of data collected with the D0 detector from Fermilab Tevatron Collider p (p) over bar collisions at root s = 1.96 TeV. The measured mass difference of 3.8 +/- 3.7 GeV is consistent with the equality of t and (t) over bar masses. This is the first direct measurement of a mass difference between a quark and its antiquark partner.

  • 321. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Direct Measurement of the W Boson Width2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 23, p. 231802-Article in journal (Refereed)
    Abstract [en]

    We present a direct measurement of the width of the W boson using the shape of the transverse mass distribution of W -> e nu candidate events. Data from approximately 1 fb(-1) of integrated luminosity recorded at s=1.96 TeV by the D0 detector at the Fermilab Tevatron pp collider are analyzed. We use the same methods and data sample that were used for our recently published W boson mass measurement, except for the modeling of the recoil, which is done with a new method based on a recoil library. Our result, 2.028 +/- 0.072 GeV, is in agreement with the predictions of the standard model.

  • 322. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor, MI .
    Zverev, E. G.
    et al.,
    Measurement of Dijet Angular Distributions at s=1.96 TeV and Searches for Quark Compositeness and Extra Spatial Dimensions2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 19, p. 191803-Article in journal (Refereed)
    Abstract [en]

    We present the first measurement of dijet angular distributions in pp collisions at s=1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a dataset corresponding to an integrated luminosity of 0.7 fb(-1) collected with the D0 detector. Dijet angular distributions have been measured over a range of dijet masses, from 0.25 TeV to above 1.1 TeV. The data are in good agreement with the predictions of perturbative QCD and are used to constrain new physics models including quark compositeness, large extra dimensions, and TeV(-1) scale extra dimensions. For all models considered, we set the most stringent direct limits to date.

  • 323. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Measurement of the W Boson Mass2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 14, p. 141801-Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the W boson mass in W -> e nu decays using 1 fb(-1) of data collected with the D0 detector during Run II of the Fermilab Tevatron collider. With a sample of 499830 W -> e nu candidate events, we measure M(W)=80.401 +/- 0.043 GeV. This is the most precise measurement from a single experiment.

  • 324. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Measurement of the WW Production Cross Section with Dilepton Final States in pp Collisions at s=1.96 TeV and Limits on Anomalous Trilinear Gauge Couplings2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 19, p. 191801-Article in journal (Refereed)
    Abstract [en]

    We provide the most precise measurement of the WW production cross section in pp collisions to date at a center of mass energy of 1.96 TeV, and set limits on the associated trilinear gauge couplings. The WW -> l nu l(')nu (l, l(')=e, mu) decay channels are analyzed in 1 fb(-1) of data collected by the D0 detector at the Fermilab Tevatron Collider. The measured cross section is sigma(pp -> WW)=11.5 +/- 2.1(stat+syst)+/- 0.7(lumi) pb. One- and two-dimensional 95% C.L. limits on trilinear gauge couplings are provided.

  • 325. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Observation of Single Top-Quark Production2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 9, p. 092001-Article in journal (Refereed)
    Abstract [en]

    We report observation of the electroweak production of single top quarks in pp collisions at s=1.96 TeV based on 2.3 fb(-1) of data collected by the D0 detector at the Fermilab Tevatron Collider. Using events containing an isolated electron or muon and missing transverse energy, together with jets originating from the fragmentation of b quarks, we measure a cross section of sigma(pp -> tb+X,tqb+X)=3.94 +/- 0.88 pb. The probability to measure a cross section at this value or higher in the absence of signal is 2.5x10(-7), corresponding to a 5.0 standard deviation significance for the observation.

  • 326. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Search for a Resonance Decaying into WZ Boson Pairs in p(p)over-bar Collisions2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, no 6, p. 061801-Article in journal (Refereed)
    Abstract [en]

    We present the first search for an electrically charged resonance W' decaying to a WZ boson pair using 4.1 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron p (p) over bar collider. The WZ pairs are reconstructed through their decays into three charged leptons (l = e, mu). A total of 9 data events is observed in good agreement with the background prediction. We set 95% C.L. limits on the W'WZ coupling and on the W' production cross section multiplied by the branching fractions. We also exclude W' masses between 188 and 520 GeV within a simple extension of the standard model and set the most restrictive limits to date on low-scale technicolor models.

  • 327. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for Dark Photons from Supersymmetric Hidden Valleys2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 8, p. 081802-Article in journal (Refereed)
    Abstract [en]

    We search for a new light gauge boson, a dark photon, with the D0 experiment. In the model we consider, supersymmetric partners are pair produced and cascade to the lightest neutralinos that can decay into the hidden sector state plus either a photon or a dark photon. The dark photon decays through its mixing with a photon into fermion pairs. We therefore investigate a previously unexplored final state that contains a photon, two spatially close leptons, and large missing transverse energy. We do not observe any evidence for dark photons and set a limit on their production.

  • 328. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Search for Higgs Boson Production in Dilepton and Missing Energy Final States with 5.4 fb(-1) of p(p)over-bar Collisions at root s=1.96 TeV2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, no 6, p. 061804-Article in journal (Refereed)
    Abstract [en]

    A search for the standard model Higgs boson is presented using events with two charged leptons and large missing transverse energy selected from 5.4 fb(-1) of integrated luminosity in p ($) over bar collisions at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron collider. No significant excess of events above background predictions is found, and observed (expected) upper limits at 95% confidence level on the rate of Higgs boson production are derived that are a factor of 1.55 (1.36) above the predicted standard model cross section at m(H) = 165 GeV.

  • 329. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for Next-to-Minimal Supersymmetric Higgs Bosons in the h -> aa ->mu mu mu mu, mu mu tau tau Channels Using pp Collisions at s=1.96 TeV2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 6, p. 061801-Article in journal (Refereed)
    Abstract [en]

    We report on a first search for production of the lightest neutral CP-even Higgs boson (h) in the next-to-minimal supersymmetric standard model, where h decays to a pair of neutral pseudoscalar Higgs bosons (a), using 4.2 fb(-1) of data recorded with the D0 detector at Fermilab. The a bosons are required to either both decay to mu(+)mu(-) or one to mu(+)mu(-) and the other to tau(+)tau(-). No significant signal is observed, and we set limits on its production as functions of M(a) and M(h).

  • 330. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Search for Resonant Diphoton Production with the D0 Detector2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 23, p. 231801-Article in journal (Refereed)
    Abstract [en]

    We present a search for a narrow resonance in the inclusive diphoton final state using similar to 2.7 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider. We observe good agreement between the data and the background prediction, and set the first 95% C. L. upper limits on the production cross section times the branching ratio for decay into a pair of photons for resonance masses between 100 and 150 GeV. This search is also interpreted in the context of several models of electroweak symmetry breaking with a Higgs boson decaying into two photons.

  • 331. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Search for Resonant Pair Production of Neutral Long-Lived Particles Decaying to b(b)over-bar in p(p)over-bar Collisions at root s=1.96 TeV2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 7, p. 071801-Article in journal (Refereed)
    Abstract [en]

    We report on a first search for resonant pair production of neutral long-lived particles (NLLP) which each decay to a b (b) over bar pair, using 3.6 fb(-1) of data recorded with the D0 detector at the Fermilab Tevatron collider. We search for pairs of displaced vertices in the tracking detector at radii in the range 1.6-20 cm from the beam axis. No significant excess is observed above background, and upper limits are set on the production rate in a hidden-valley benchmark model for a range of Higgs boson masses and NLLP masses and lifetimes.

  • 332. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Search for the Associated Production of a b Quark and a Neutral Supersymmetric Higgs Boson that Decays into tau Pairs2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, no 15, p. 151801-Article in journal (Refereed)
    Abstract [en]

    We report results from a search for production of a neutral Higgs boson in association with a b quark. We search for Higgs decays to tau pairs with one tau subsequently decaying to a muon and the other to hadrons. The data correspond to 2: 7 fb(-1) of p (p) over bar collisions recorded by the D0 detector at.. root s = 1.96 TeV. The data are found to be consistent with background predictions. The result allows us to exclude a significant region of parameter space of the minimal supersymmetric model.

  • 333. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Search for the Standard Model Higgs Boson in Tau Final States2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 25, p. 251801-Article in journal (Refereed)
    Abstract [en]

    We present a search for the standard model Higgs boson using hadronically decaying tau leptons, in 1 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron pp collider. We select two final states: tau(+/-) plus missing transverse energy and b jets, and tau(+)tau(-) plus jets. These final states are sensitive to a combination of associated W/Z boson plus Higgs boson, vector boson fusion, and gluon-gluon fusion production processes. The observed ratio of the combined limit on the Higgs production cross section at the 95% C.L. to the standard model expectation is 29 for a Higgs boson mass of 115 GeV.

  • 334. Abazov, V. M.
    et al.
    Strandberg, Jonas
    Univ Michigan, Ann Arbor.
    Zverev, E. G.
    et al.,
    Search for the Standard Model Higgs Boson in the ZH -> v(v)over-barb(b)over-bar Channel in 5.2 fb(-1) of p(p)over-bar Collisions at root s=1.96 TeV2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, no 7, p. 071801-Article in journal (Refereed)
    Abstract [en]

    A search is performed for the standard model Higgs boson in 5.2 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV, collected with the D0 detector at the Fermilab Tevatron Collider. The final state considered is a pair of b jets and large missing transverse energy, as expected from p (p) over bar -> ZH -> v (v) over barb (b) over bar production. The search is also sensitive to the WH -> lvb (b) over bar channel when the charged lepton is not identified. For a Higgs boson mass of 115 GeV, a limit is set at the 95% C.L. on the cross section multiplied by branching fraction for [p (p) over bar -> (Z/W)H](H -> b (b) over bar) that is a factor of 3.7 larger than the standard model value, consistent with the factor of 4.6 expected.

  • 335. Abazov, V. M.
    et al.
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Evidence of WW and WZ Production with lepton plus jets Final States in pp Collisions at root s=1.96 TeV2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 16, p. 161801-Article in journal (Refereed)
    Abstract [en]

    We present first evidence for WW+WZ production in lepton+jets final states at a hadron collider. The data correspond to 1.07 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron in pp collisions at root s=1.96 TeV. The observed cross section for WW+WZ production is 20.2 +/- 4.5 pb, consistent with the standard model and more precise than previous measurements in fully leptonic final states. The probability that background fluctuations alone produce this excess is < 5.4x10(-6), which corresponds to a significance of 4.4 standard deviations.

  • 336. Abazov, V. M.
    et al.
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Measurement of gamma + b + X and gamma + c + X Production Cross Sections in pp > Collisions at s=1.96 TeV2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 19, p. 192002-Article in journal (Refereed)
    Abstract [en]

    First measurements of the differential cross sections d(3)sigma/(dp(T)(gamma)dy(gamma)dy(jet)) for the inclusive production of a photon in association with a heavy quark (b, c) jet are presented, covering photon transverse momenta 30 < p(T)(gamma)< 150 GeV, photon rapidities |y(gamma)|< 1.0, jet rapidities |y(jet)|< 0.8, and jet transverse momenta p(T)(jet)> 15 GeV. The results are based on an integrated luminosity of 1 fb(-1) in pp collisions at s=1.96 TeV recorded with the D0 detector at the Fermilab Tevatron Collider. The results are compared with next-to-leading order perturbative QCD predictions.

  • 337. Abazov, V. M.
    et al.
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et. al.,
    Measurement of the Z gamma -> nu(nu)over-bar gamma Production Cross Section and Limits on Anomalous ZZ gamma and Z gamma gamma Couplings in p(p)over-bar Collisions at root s=1.96 TeV2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 20, p. 201802-Article in journal (Refereed)
    Abstract [en]

    We present the first observation of the Z gamma -> nu(nu) over bar gamma process at the Fermilab Tevatron at 5.1 standard deviations significance, based on 3.6 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider at root s = 1.96 TeV. The measured Z gamma production cross section multiplied by the branching fraction of Z -> nu(nu) over bar is 32 +/- 9(stat + syst) +/- 2(lumi) fb for the photon E(T) > 90 GeV. It is in agreement with the standard model prediction of 39 +/- 4 fb. We set limits on anomalous trilinear Z gamma gamma and ZZ gamma gauge boson couplings, most of which are the most restrictive to date.

  • 338. Abazov, V. M.
    et al.
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for Anomalous Top-Quark Couplings with the D0 Detector2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 9, p. 092002-Article in journal (Refereed)
    Abstract [en]

    Anomalous Wtb couplings modify the angular correlations of the top-quark decay products and change the single top-quark production cross section. We present limits on anomalous top-quark couplings by combining information from W boson helicity measurements in top-quark decays and anomalous coupling searches in the single top-quark final state. We set limits on right-handed vector couplings as well as left-handed and right-handed tensor couplings based on about 1 fb(-1) of data collected by the D0 experiment.

  • 339. Abazov, V. M.
    et al.
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for Long-Lived Charged Massive Particles with the D0 Detector2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 16, p. 161802-Article in journal (Refereed)
    Abstract [en]

    We search for long-lived charged massive particles using 1.1 fb(-1) of data collected by the D0 detector at the Fermilab Tevatron pp Collider. Time-of-flight information is used to search for pair produced long-lived tau sleptons, gauginolike charginos, and Higgsino-like charginos. We find no evidence of a signal and set 95% C.L. cross section upper limits for staus, which vary from 0.31 to 0.04 pb for stau masses between 60 and 300 GeV. We also set lower mass limits of 206 GeV (171 GeV) for pair produced charged gauginos (Higgsinos).

  • 340. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Direct observation of the strange b baryon Xi(-)(b)2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 5, p. 052001-1-052001-8Article in journal (Refereed)
    Abstract [en]

    We report the first direct observation of the strange b baryon Xi(-)(b)(Xi) over bar (+)(b)). We reconstruct the decay Xi(-)(b)-->J/psi Xi(-), with J/psi-->mu(+)mu(-), and Xi(-)-->Lambda pi(-)-->p pi(-)pi(-) in p (p) over bar collisions at root s = 1.96 TeV. Using 1.3 fb(-1) of data collected by the D0 detector, we observe 15.2 +/- 4.4(stat)(-0.4)(+1.9)(syst) Xi(-)(b) candidates at a mass of 5.774 +/- 0.011(stat) +/- 0.015(syst) GeV. The significance of the observed signal is 5.5 sigma, equivalent to a probability of 3.3 x 10(-8) of it arising from a background fluctuation. Normalizing to the decay Lambda(b)-->J/psi Lambda, we measure the relative rate sigma(Xi(-)(b))xB(Xi(-)(b)-->J/psi Xi)/ sigma(Lambda(b))xB(Lambda(b)-->J/psi Lambda) = 0.28 +/- 0.09(stat)(-0.08)(+0.09)(syst).

  • 341. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Evidence for production of single top quarks and first direct measurement of vertical bar V-tb vertical bar2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 18, p. 181802-1-181802-8Article in journal (Refereed)
    Abstract [en]

    The D0 Collaboration presents first evidence for the production of single top quarks at the Fermilab Tevatron < p(p)over bar > collider. Using a 0.9 fb(-1) dataset, we apply a multivariate analysis to separate signal from background and measure sigma(< p(p)over bar >-> tb+X,tqb+X)=4.9 +/- 1.4 pb. The probability to measure a cross section at this value or higher in the absence of a signal is 0.035%, corresponding to a 3.4 standard deviation significance. We use the cross section measurement to directly determine the Cabibbo-Kobayashi-Maskawa matrix element that describes the Wtb coupling and find 0.68 <vertical bar V-tb vertical bar <= 1 at 95% C.L. within the standard model.

  • 342. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Lifetime difference and CP-violating phase in the B-s(0) system2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 12, p. 121801-1-121801-7Article in journal (Refereed)
    Abstract [en]

    From an analysis of the decay B-s(0)-> J/psi phi, we obtain the width difference between the light and heavy mass eigenstates Delta Gamma equivalent to(Gamma(L)-Gamma(H))=0.17 +/- 0.09(stat)+/- 0.02(syst) ps(-1) and the CP-violating phase phi(s)=-0.79 +/- 0.56(stat)(-0.01)(+0.14)(syst). Under the hypothesis of no CP violation (phi(s)equivalent to 0), we obtain 1/Gamma=tau/(B-s(0))=1.52 +/- 0.08(stat)(-0.03)(+0.01)(syst) ps and Delta Gamma=0.12(-0.10)(+0.08)(stat)+/- 0.02(syst) ps(-1). The data sample corresponds to an integrated luminosity of about 1.1 fb(-1) accumulated with the D0 detector at the Fermilab Tevatron collider. This is the first direct measurement of the CP-violating mixing phase in the B-s(0) system.

  • 343. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Measurement of the charge asymmetry in semileptonic B-s(0) decays2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 15, p. 151801-1-151801-7Article in journal (Refereed)
    Abstract [en]

    We have performed the first direct measurement of the time-integrated flavor untagged charge asymmetry in semileptonic B-s(0) decays A(SL)(s,unt) by comparing the decay rate of B-s(0) -> mu(+) D-s(-) nu X, where D-s(-) -> phi pi(-) and phi -> K+K-, with the charge-conjugate (B) over bar (0)(s) decay rate. This sample was selected from 1: 3 fb(-1) of data collected by the D0 experiment in run II of the Fermilab Tevatron collider. We obtain A(SL)(s,unt) = [1.23 +/- 0.97(stat) +/- 0.17(syst)] x 10(-2). Assuming that Delta m(s)/(Gamma) over bar (s) >> 1, this result can be translated into a measurement of the CP-violating phase in B-s(0) mixing: Delta Gamma(s)/Delta m(s) tan phi(s) = [2.45 +/- 1.93(stat) +/- 0.35(syst)] x 10(-2).

  • 344. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Measurement of the Lambda(0)(b) lifetime using semileptonic decays2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 18, p. 182001-1-182001-7Article in journal (Refereed)
    Abstract [en]

    We report a measurement of the Lambda(0)(b) lifetime using a sample corresponding to 1.3 fb(-1) of data collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron collider. The Lambda(0)(b) baryon is reconstructed via the decay Lambda(0)(b)->mu(nu) over bar Lambda X-+(c). Using 4437 +/- 329 signal candidates, we measure the Lambda(0)(b) lifetime to be tau(Lambda(0)(b))=1.290(-0.110)(+0.119)(stat)(-0.091)(+0.087)(syst) ps, which is among the most precise measurements in semileptonic Lambda(0)(b) decays. This result is in good agreement with the world average value.

  • 345. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Measurement of the Lambda(b) lifetime in the exclusive decay Lambda(b)-> J/psi Lambda2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 14, p. 142001-1-142001-7Article in journal (Refereed)
    Abstract [en]

    We have measured the Lambda(b) lifetime using the exclusive decay Lambda(b)-> J/psi Lambda, based on 1.2 fb(-1) of data collected with the D0 detector during 2002-2006. From 171 reconstructed Lambda(b) decays, where the J/psi and Lambda are identified via the decays J/psi ->mu(+)mu(-) and Lambda -> p pi, we measured the Lambda(b) lifetime to be tau(Lambda(b))=1.218(-0.115)(+0.130)(stat)+/- 0.042(syst) ps. We also measured the B-0 lifetime in the decay B-0 -> J/psi(mu(+)mu(-))K-S(0)(pi(+)pi(-)) to be tau(B-0)=1.501(-0.074)(+0.078)(stat)+/- 0.050(syst) ps, yielding a lifetime ratio of tau(Lambda(b))/tau(B-0)=0.811(-0.087)(+0.096)(stat)+/- 0.034(syst).

  • 346. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Properties of l=1 B-1 and B*(2) Mesons2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 17, p. 172001-1-172001-7Article in journal (Refereed)
    Abstract [en]

    This Letter presents the first strong evidence for the resolution of the excited B mesons B-1 and B-2(*) as two separate states in fully reconstructed decays to B+(*())pi(-). The mass of B-1 is measured to be 5720.6 +/- 2.4 +/- 1.4 MeV/c(2) and the mass difference Delta M between B-2* and B-1 is 26.2 +/- 3.1 +/- 0: 9 MeV/c(2), giving the mass of the B-2* as 5746.8 +/- 2.4 +/- 1.7 MeV/c(2). The production rate for B-1 and B-2* mesons is determined to be a fraction (13.9 +/- 1.9 +/- 3.2)% of the production rate of the B+ meson.

  • 347. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for production of single top quarks via tcg and tug flavor-changing-neutral-current couplings2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 19, p. 191802-1-191802-8Article in journal (Refereed)
    Abstract [en]

    We search for the production of single top quarks via flavor-changing-neutral-current couplings of a gluon to the top quark and a charm (c) or up (u) quark. We analyze 230 pb(-1) of lepton+jets data from p (p) over tilde collisions at a center of mass energy of 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. We observe no significant deviation from standard model predictions, and hence set upper limits on the anomalous coupling parameters kappa(c)(g)/Lambda and kappa(u)(g)/Lambda, where kappa(g) define the strength of tcg and tug couplings, and Lambda defines the scale of new physics. The limits at 95% C.L. are kappa(c)(g)/Lambda < 0.15 TeV-1 and kappa(u)(g)/Lambda < 0.037 TeV-1.

  • 348. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for stopped gluinos from p(p)over-bar collisions at root s=1.96 TeV2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 13, p. 131801-1-131801-8Article in journal (Refereed)
    Abstract [en]

    Long-lived, heavy particles are predicted in a number of models beyond the standard model of particle physics. We present the first direct search for such particles' decays, occurring up to 100 h after their production and not synchronized with an accelerator bunch crossing. We apply the analysis to the gluino (g), predicted in split supersymmetry, which after hadronization can become charged and lose enough momentum through ionization to come to rest in dense particle detectors. Approximately 410 pb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected with the D0 detector during Run II of the Fermilab Tevatron collider are analyzed in search of such "stopped gluinos" decaying into a gluon and a neutralino ((chi) over tilde (0)(1)). Limits are placed on the (gluino cross section) x (probability to stop) x [BR((g) over tilde -> g (chi) over tilde (0)(1))] as a function of the gluino and (chi) over tilde (0)(1) masses, for gluino lifetimes from 30 mu s-100 h.

  • 349. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for techniparticles in e plus jets events at D02007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 22, p. 221801-1-221801-7Article in journal (Refereed)
    Abstract [en]

    We search for the technicolor process p(p) over bar ->rho(T)/omega(T)-> W pi(T) in events containing one electron and two jets, in data corresponding to an integrated luminosity of 390 pb(-1), recorded by the D0 experiment at the Fermilab Tevatron. Technicolor predicts that technipions pi(T) decay dominantly into b(b) over bar, b(c) over bar, or (b) over barc, depending on their charge. In these events b and c quarks are identified by their secondary decay vertices within jets. Two analysis methods based on topological variables are presented. Since no excess above the standard model prediction was found, the result is presented as an exclusion in the pi(T) vs rho(T) mass plane for a given set of model parameters.

  • 350. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for third-generation scalar leptoquarks in p(p)over-bar collisions at root s=1.96 TeV2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 6, p. 061801-1-061801-7Article in journal (Refereed)
    Abstract [en]

    We report on a search for charge-1/3 third-generation leptoquarks (LQ) produced in p (p) over bar collisions at root s =1.96 TeV using the D0 detector at Fermilab. Third-generation leptoquarks are assumed to be produced in pairs and to decay to a tau neutrino and a b quark with branching fraction B. We place upper limits on sigma(p (p) over bar -> LQ (LQ) over bar )B-2 as a function of the leptoquark mass M-LQ. Assuming B=1, we exclude at the 95% confidence level third-generation scalar leptoquarks with M-LQ < 229 GeV.

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