Chr.V. Christov

Baryons as non-topological chiral solitons

Abstract The present review gives a survey of recent developments and applications of the Nambu-Jona-Lasinio model with Nf = 2 and Nf = 3 quark flavors for the structure of baryons. The model is an effective chiral quark theory which incorporates the SU(Nf)L⊗SU(Nf)R⊗U(1)V approximate symmetry of Quantum chromodynamics. The approach describes the spontaneous chiral symmetry breaking and dynamical quark mass generation. Mesons appear as quark-antiquark excitations and baryons arise as non-topological solitons with three valence quarks and a polarized Dirac sea. For the evaluation of the baryon properties the present review concentrates on the non-linear Nambu-Jona-Lasinio model with quark and Goldstone degrees of freedom which is identical to the Chiral quark soliton model obtained from the instanton liquid model of the QCD vacuum. In this non-linear model, a wide variety of observables of baryons of the octet and decuplet is considered. These include, in particular, electromagnetic, axial, pseudoscalar and pion nucleon form factors and the related static properties like magnetic moments, radii and coupling constants of the nucleon as well as the mass splittings and electromagnetic form factors of hyperons. Predictions are given for the strange form factors, the scalar form factor and the tensor charge of the nucleon.

1/Nc rotational corrections to gA and isovector magnetic moment of the nucleon

The

Medium effects on nucleon properties

1/N_c

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

rotational corrections to the axial vector constant and the isovector magnetic moment of the nucleon are studied in the Nambu -- Jona-Lasinio model. We follow a semiclassical quantization procedure in terms of path integrals in which we can include perturbatively corrections in powers of angular velocity

Properties of the nucleon in the nuclear medium within a chiral quark-meson theory

\Omega \sim \frac 1{N_c}

E2M1 ratio for the γN → Δ transition in the chiral quark soliton model

. We find non-zero

Nucleon properties and restoration of chiral symmetry at finite density and temperature in an effective theory

1/N_c

Neutron-proton mass difference in a baryonic medium and the Nolen-Schiffer anomaly

order corrections from both the valence and the Dirac sea quarks. These corrections are large enough to resolve the long-standing problem of a strong underestimation of both

Medium effects on Δ properties and N-Δ transition form factors☆

g_A

Natural orbitals and occupation numbers in the coherent density fluctuation model

and