Decay properties of new D-mesons

We consider radiative and pionic decays of the new D_s-mesons in the framework of a phenomenologically motivated approach. Present data on ratios of the two kinds of decays can be described without explicit using a 4-quark component. Most probably, the isospin violation in decays of different D_s-mesons is not universal, and the binding potential should be different from Coulombic. New precise measurements may provide further clarification for the nature of the D_s excited states.

Flavor asymmetry of polarized and unpolarized sea quark distributions in the large-N_c limit

We summarize recent attempts to calculate the flavor asymmetry of the nucleons sea quark distributions in the large-$N_c$ limit, where the nucleon can be described as a soliton of an effective chiral theory. We discuss the leading-twist longitudinally polarized and transversity antiquark distributions, $Deltabar u (x) - Deltabar d (x)$ and $deltabar u (x) - deltabar d (x)$, as well as the unpolarized one, $bar u (x) - bar d (x)$, which appears only in the next-to-leading order of the $1/N_c$-expansion. Results for $bar u (x) - bar d (x)$ are in good agreement with the recent Drell-Yan data from the FNAL E866 experiment. The longitudinally polarized antiquark asymmetry, $Deltabar u (x) - Deltabar d (x)$, is found to be larger than the unpolarized one.

Electromagnetic form factors of the nucleon in the chiral quark soliton model

In this paper we present the derivation as well as the numerical results for the electromagnetic form factors of the nucleon within the chiral quark soliton model in the semiclassical quantization scheme. The model is based on semibosonized SU(2) Nambu -- Jona-Lasinio lagrangean, where the boson fields are treated as classical ones. Other observables, namely the nucleon mean squared radii, the magnetic moments, and the nucleon--$Delta$ splitting are calculated as well. The calculations have been done taking into account the quark sea polarization effects. The final results, including rotational $1/N_c$ corrections, are compared with the existing experimental data, and they are found to be in a good agreement for the constituent quark mass of about 420 MeV. The only exception is the neutron electric form factor which is overestimated.

Axial form factor in the chiral quark soliton model

We calculate the axial form factor in the chiral quark soliton (semibosonized Nambu - Jona-Lasinio) model using the semiclassical quantization scheme in the next to leading order in angular velocity. The obtained axial form factor is in a good absolute (without additional scaling) agreement with the experimental data. Both the value at the origin and the $q$-dependence of the form factor as well as the axial m.s.radius are fairly well reproduced.

Electromagnetic Nucleon Properties and Quark Sea Polarization

In this paper we present the derivation as well as the numerical results for all electromagnetic form factors of the nucleon within the chiral quark soliton model in the semiclassical quantization scheme. The model is based on a semibosonized Nambu -- Jona-Lasinio lagrangean where the boson fields are treated as classical ones. Other observables, namely the nucleon mean squared radii, the magnetic moments and the nucleon--$Delta$ splitting are calculated as well. The calculations have been done taking into account the quark sea polarization effects. The final results, including rotational $1/N_c$ corrections, are compared with the existing experimental data and they are found to be in a good agreement for the constituent quark mass of $400-420$ MeV.