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Octet baryon magnetic moments in the chiral quark model with configuration mixing
KTH, Superseded Departments, Physics.ORCID iD: 0000-0002-3525-8349
KTH, Superseded Departments, Physics.
1998 (English)In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 57, no 1, 452-464 p.Article in journal (Refereed) Published
Abstract [en]

The Coleman-Glashow sum-rule for magnetic moments is always fulfilled in the chiral quark model, independently of SU(3) symmetry breaking. This is due to the structure of the wave functions, coming from the non-relativistic quark model. Experimentally, the Coleman-Glashow sum-rule is violated by about ten standard deviations. To overcome this problem, two models of wave functions with configuration mixing are studied. One of these models violates the Coleman-Glashow sum-rule to the right degree and also reproduces the octet baryon magnetic moments rather accurately.

Place, publisher, year, edition, pages
The American Physical Society , 1998. Vol. 57, no 1, 452-464 p.
National Category
Subatomic Physics
Identifiers
URN: urn:nbn:se:kth:diva-13372DOI: 10.1103/PhysRevD.57.452ISI: 000071320700049OAI: oai:DiVA.org:kth-13372DiVA: diva2:324771
Funder
Swedish Research Council, F-AA/FU03281-310
Note
QC 20100616Available from: 2011-06-21 Created: 2010-06-16 Last updated: 2011-06-21Bibliographically approved
In thesis
1. Dynamics of quarks and leptons: theoretical Studies of Baryons and Neutrinos
Open this publication in new window or tab >>Dynamics of quarks and leptons: theoretical Studies of Baryons and Neutrinos
2000 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The Standard Model of Elementary Particle Physics (SM) is the present theoryfor the elementary particles and their interactions and is a well-established theorywithin the physics community. The SM is a combination of Quantum Chromodynamics(QCD) and the Glashow{Weinberg{Salam (GWS) electroweak model. QCDis a theory for the strong force, whereas the GWS electroweak model is a theoryfor the weak and electromagnetic forces. This means that the SM describes allfundamental forces in Nature, except for the gravitational force. However, the SMis not a nal theory and some of its problems will be discussed in this thesis.In the rst part of this thesis, several properties of baryons are studied suchas spin structure, spin polarizations, magnetic moments, weak form factors, andnucleon quark sea isospin asymmetries, using the chiral quark model (QM). TheQM is an eective chiral eld theory developed to describe low energy phenomena of baryons, since perturbative QCD is not applicable at low energies. The resultsof the QM are in good agreement with experimental data.The second part of the thesis is devoted to the concept of quantum mechanicalneutrino oscillations. Neutrino oscillations can, however, not occur within the GWSelectroweak model. Thus, this model has to be extended in some way. All studiesincluding neutrino oscillation are done within three avor neutrino oscillationmodels. Both vacuum and matter neutrino oscillations are considered. Especially,global ts to all data of candidates for neutrino oscillations are presented and alsoan analytical formalism for matter enhanced three avor neutrino oscillations usingtime evolution operators is derived. Furthermore, investigations of matter eectswhen neutrinos traverse the Earth are included.The thesis begins with an introductory review of the QM and neutrino oscillationsand ends with the research results, which are given in the nine accompanyingscientic articles.

Place, publisher, year, edition, pages
Stockholm: KTH, 2000. xiv, 152 p.
Series
Trita-FYS, ISSN 0280-316X ; 8045
Keyword
Chiral quark model, baryons, conguration mixing, magnetic moments, Coleman{Glashow sum-rule, spin structure, spin polarizations, weak form factors, semileptonic decays, nucleon quark sea isospin asymmetry; neutrinos, neutrino oscillations, neutrino avors, mixing angles, mass squared dierences, MSW eect; numerical calculations, interpretation of experiments
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-2991 (URN)91-7170-537-6 (ISBN)
Public defence
2000-06-09, 00:00
Note
QC 20100616Available from: 2000-06-08 Created: 2000-06-08 Last updated: 2010-06-16Bibliographically approved
2. Properties of baryons in the chiral quark model
Open this publication in new window or tab >>Properties of baryons in the chiral quark model
1997 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

In this thesis, several properties of baryons are studied using the chiral quark model. The chiral quark model is a theory which can be used to describe low energy phenomena of baryons.

In Paper 1, the chiral quark model is studied using wave functions with configuration mixing. This study is motivated by the fact that the chiral quark model cannot otherwise break the Coleman–Glashow sum-rule for the magnetic moments of the octet baryons, which is xperimentally broken by about ten standard deviations. Configuration mixing with quark-diquark components is also able to reproduce the octet baryon magnetic moments very accurately.

In Paper 2, the chiral quark model is used to calculate the decuplet baryon magnetic moments. The values for the magnetic moments of the ++and− are in good agreement with the experimental results. The total quark spin polarizations are also calculated and are found to be significantly smaller than the non-relativistic quark model results.

In Paper 3, the weak form factors for semileptonic octet baryon decays are studied in the chiral quark model. The “weak magnetism” form factors are found to be consistent with the conserved vector current (CVC) results and the induced pseudotensor form factors, which seem to be model independent, are small. The results obtained are in general agreement with experiments and are also compared with other model calculations.

Place, publisher, year, edition, pages
Stockholm: KTH, 1997. viii, 52 p.
Series
Trita-FYS, ISSN 0280-316X ; 8026
Keyword
Chiral quark model, baryons, configuration mixing, magnetic moments, Coleman-Glashow sum-rule, spin polarizations, weak form factors, semilepronic decays
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-756 (URN)KTH/FYS/TEO/R--97/9--SE (ISRN)91-7170-211-3 (ISBN)
Note
QC 20100618Available from: 2000-09-26 Created: 2000-09-26 Last updated: 2011-06-20Bibliographically approved

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Publisher's full textPhysical Review Dhttp://arxiv.org/abs/hep-ph/9709353

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