No Arabic abstract
Latest results from a study of baryon ground and resonant states within relativistic constituent quark models are reported. After recalling some typical spectral properties, the description of ground states, especially with regard to the nucleon and hyperon electromagnetic structures, is addressed. In the following, recent covariant predictions for pion, eta, and kaon partial decay widths of light and strange baryon resonances below 2 GeV are summarized. These results exhibit a characteristic pattern that is distinct from nonrelativistic or relativized decay studies performed so far. Together with a detailed analysis of the spin, flavor, and spatial structures of the wave functions, it supports a new and extended classification scheme of baryon ground and resonant states into SU(3) flavor multiplets.
We present a new classification scheme of baryon ground states and resonances into SU(3) flavor multiplets. The scheme is worked out along a covariant formalism with relativistic constituent quark models and it relies on detailed investigations of the baryon spectra, the spin-flavor structure of the baryon eigenstates, the behaviour of their probability density distributions as well as covariant predictions for mesonic decay widths. The results are found to be quite independent of the specific types of relativistic constituent quark models employed. It turns out that a consistent classification requires to include also resonances that are presently reported from experiment with only two-star status.
The reactions $Sigma_b^* to Lambda_b pi$, $Sigma_b to Lambda_b pi$, and $Xi_b^* to Xi_b pi$ are studied in the $^3P_0$ non-relativistic quark model with all the model parameters fixed in the sector of light quarks. The theoretical predictions for the decay widths $Gamma_{Sigma_b^* to Lambda_b pi}$ and $Gamma_{Sigma_b to Lambda_b pi}$ are consistent with the experimental data of the CDF Collaboration. Using as an input the recent mass of $Xi_b$ and the theoretical predictions mass of $Xi_b^{*}$, a narrow decay width about 1 MeV is predicted for the bottom baryon $Xi_b^*$. The work suggests that the $^3P_0$ quark dynamics is of independence of environments where heavy quarks may or may not be a component of baryons.
Exclusive semileptonic decays of bottom and charm baryons are considered within a relativistic three-quark model with a Gaussian shape for the baryon-three-quark vertex and standard quark propagators. We calculate the baryonic Isgur-Wise functions, decay rates and asymmetry parameters.
A simple TeV scale model for baryon and lepton number violation is presented, where neutrino mass arises via a one-loop radiative seesaw effect and B-violation obeys $Delta B=2$ selection rule. The stability of proton is connected to the neutrino mass generation. Matter-antimatter asymmetry is generated in this model via resonant baryogenesis mechanism.
Using the colored quark cluster model, we study magnetic moments of the octet baryons. We give the values of the magnetic moments of baryons $p$, $n$, $Sigma^+$, $Sigma^-$, $Xi^0$, and $Xi^-$. The results also show that the orbital motion has very significant effects on the spin and magnetic moments of those baryons and the strange component in the proton is very small.