Phase diagram of neutron star quark matter in nonlocal chiral models

We analyze the phase diagram of two-flavor quark matter under neutron star constraints for a nonlocal covariant quark model within the mean-field approximation. Applications to cold compact stars are discussed.     

Photoproduction of positive-parity excited baryons in the 1/Nc expansion of QCD

We analyze the photoproduction helicity amplitudes for positive-parity excited baryons in the context of the 1/N(c) expansion of QCD. The results show that subleading corrections in 1/N(c) are important and that, while one-body effective operators are dominant, there is some evidence for the need for two-body effects.     

Nonlocality effects in the phase diagram of neutral quark matter

We construct phase diagrams of two-flavor quark matter under compact star constraints for two nonlocal, covariant quark models (instanton liquid and one-gluon exchange (OGE) inspired) within the mean field approximation and compare the results for different diquark coupling strengths. For the OGE model, stable hybrid stars with quark cores are obtained. The text was submitted by the authors in English.     

Deconfinement and chiral restoration in non-local PNJL models at zero and imaginary chemical potential

We study the deconfinement and chiral restoration transitions in the context of non-local PNJL models, considering the impact of the presence of dynamical quarks on the scale parameter appearing in the Polyakov potential. We show that the corresponding critical temperatures are naturally entangled for both zero and imaginary chemical potential, in good agreement with lattice QCD results. We also analyze the Roberge-Weiss transition, which is found to be first order at the associated endpoint.     

The applicability of nuclear field theory to shell-model calculations

Previous NFT calculations of the four-particle spectrum reached different conclusions concerning the applicability of the lowest-order Rayleigh-Schroedinger perturbation expansion. In the present paper, we show that the inclusion of second-order diagrams and/or diagonalization procedures yields satisfactory results both for the energies and for the transfer matrix elements even for j-shells as small as the $\text{j =}\text{7}\text{2}$ and $\text{j =}\text{11}\text{2}$ shells.     

Decays of excited baryons in the large- N<Subscript>c</Subscript> expansion of QCD

We present the analysis of the decay widths of excited baryons in the framework of the 1/N _c expansion of QCD. These studies are performed up to order 1/N _c and include both positive- and negative-parity excited baryons.     

Masses of the 70(-) baryons in large N(c) QCD

The masses of the negative parity 70-plet baryons are analyzed in large N(c) QCD to order 1/N(c) and to first order in SU(3) symmetry breaking. The existing experimental data are well reproduced and 20 new observables are predicted. The leading order SU(6) spin-flavor symmetry breaking is small and, as it occurs in the quark model, the subleading in 1/N(c) hyperfine interaction is the dominant source of the breaking. It is found that the Lambda(1405) and Lambda(1520) are well described as three-quark states and spin-orbit partners. New relations between splittings in different SU(3) multiplets are found.