Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Strong interaction physics (quark and hadron structure)

Expertise on the Nambu-Jona-Lasinio model with separable interactions (NJL-SI) and on the quark confinement model (QCM) are exploited to address the following questions in the confining regime of quantum-chromodynamics: magnetic form factors, magnetic moments and semileptonic coupling constants of low-lying baryons; weak semileptonic decays of kaons and pions.

The electromagnetic form factors of nucleons in a relativistic three-quark model have been studied within a relativistic three-quark model with a Gaussian shape for the nucleon-quark vertex. Values for magnetic moments and electromagnetic radii agreed well with the experimental data at low Q2. However, the model underestimates the electromagnetic form factors at high momentum transfers for the calculated range 0Q21 GeV2. The * 0 form factor was obtained within the Lagrangian quark model with separable interaction. The pion-quarks vertex was chosen in a Gaussian form. The form factor obtained is close to the available experimental data from the CLEO Coll. and reaches smoothly the Brodsky-Lepage limit at Q2 = 10 GeV2. A perturbation-theory for the + - atom has been developed for calculation of the characteristics of the pionic atom on the basis of the field-theoretic Bethe-Salpeter approach. A closed expression was obtained for the first order correction to the lifetime of the + - atom. The Q2-dependence of heavy-to-light form factors in the full physical region was obtained within the relativistic quark model with heavy infrapropagators. The behaviour of the vector form factors agrees with the pole dominance hypothesis whereas the behaviour of the axial form factors is rather different from the pole-like function. Heavy baryon transitions in a relativistic three-quark model. Exclusive semileptonic decays of bottom and charm baryons have been considered within a relativistic three-quark model of Gaussian shape for the baryon-three-quark vertex and standard quark propagators. The baryonic Isgur-Wise functions, decay rates, and asymmetry parameters have been calculated.

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Paul Scherrer Institute
5232 Villigen
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