78 documents found, page 1 of 8
Many-body theory for systems of composite hadrons
Krein, G. [UNESP]Made available in DSpace on 2022-04-28T19:55:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2000-12-01; Many-body systems of composite hadrons are characterized by processes that involve the simultaneous presence of hadrons and their constituents. We briefly review several methods that have been devised to study such systems and present a novel method that is based on the ideas of mapping between physical...
Chiral corrections to baryon properties with composite pions
Bicudo, P. J.A.; Krein, G. [UNESP]; Ribeiro, J. E.F.T.Made available in DSpace on 2022-04-28T19:56:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-01-01; A calculational scheme is developed to evaluate chiral corrections to properties of composite baryons with composite pions. The composite baryons and pions are bound states derived from a microscopic chiral quark model. The model is amenable to standard many-body techniques such as the BCS and random ph...
Long- and medium-range components of the nuclear force in quark-model based cal...
Hadjimichef, D.; Haidenbauer, J.; Krein, G. [UNESP]Made available in DSpace on 2022-04-28T19:56:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-01-01; Quark-model descriptions of the nucleon-nucleon interaction contain two main ingredients, a quark-exchange mechanism for the short-range repulsion and meson exchanges for the medium- and long-range parts of the interaction. We point out the special role played by higher partial waves, and in particular ...
Hadron masses in a chirally symmetric confining model
Bicudo, P. J.A.; Krein, G. [UNESP]; Ribeiro, J. E.F.T.; Villate, J. E.Made available in DSpace on 2022-04-28T20:01:18Z (GMT). No. of bitstreams: 0 Previous issue date: 1992-01-01; Hadron masses are investigated in the framework of a chirally invariant, effective quark Hamiltonian. The hyperfine, spin-orbit, and tensor forces are found to be connected to the chiral angle, which measures the extent of vacuum condensation. The only finite eigenvalues of this Hamiltonian are shown to...
Cutoff-independent regularization of four-fermion interactions for color superc...
Farias, R. L.S. [UNESP]; Dallabona, G. [UNESP]; Krein, G. [UNESP]; Battistel, O. A.Made available in DSpace on 2022-04-28T20:07:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-01-01; We implement a cutoff-independent regularization of four-fermion interactions to calculate the color-superconducting gap parameter in quark matter. The traditional cutoff regularization has difficulties for chemical potentials μ of the order of the cutoff Λ, predicting in particular a vanishing gap at μ...
Back-to-back correlations for finite expanding fireballs
Padula, Sandra S. [UNESP]; Krein, G. [UNESP]; Csörgo, T.; Hama, Y.; Panda, P. K.Made available in DSpace on 2022-04-28T20:07:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-01-01; Back-to-back correlations of particle-antiparticle pairs are related to the in-medium mass-modification and squeezing of the quanta involved. They are predicted to appear when hot and dense hadronic matter is formed in high energy nucleus-nucleus collisions. The survival and magnitude of the back-to-bac...
Medium effects on spin observables of proton knockout reactions
Krein, G. [UNESP]; Maris, Th A.J.; Rodrigues, B. B.; Veit, E. A.Made available in DSpace on 2022-04-28T19:53:15Z (GMT). No. of bitstreams: 0 Previous issue date: 1995-01-01; Medium modifications of the properties of bound nucleons and mesons are investigated by means of intermediate energy quasifree proton knockout reactions with polarized incident protons, by comparison of quantities which are insensitive against wave distortions. The sensitivity of the spin observables of...
Ghost poles in the nucleon propagator: Vertex corrections and form factors
Krein, G. [UNESP]; Nielsen, M.; Puff, R. D.; Wilets, L.Made available in DSpace on 2022-04-28T19:53:15Z (GMT). No. of bitstreams: 0 Previous issue date: 1993-01-01; Vertex corrections are taken into account in the Schwinger-Dyson equation for the nucleon propagator in a relativistic field theory of fermions and mesons. The usual Hartree-Fock approximation for the nucleon propagator is known to produce the appearance of complex (ghost) poles which violate basic theo...
Relating the QCD Pomeron to an effective gluon mass
Halzen, F.; Krein, G. [UNESP]; Natale, A. A. [UNESP]Made available in DSpace on 2022-04-28T19:53:18Z (GMT). No. of bitstreams: 0 Previous issue date: 1993-01-01; We construct the Pomeron as an exchange of two nonperturbative gluons, where the nonperturbative gluon propagator is described by an approximate solution of the Schwinger-Dyson equation which contains a dynamically generated gluon mass. We compute the total and elastic differential (dσdt) cross sections...
Self-consistent solution of the Schwinger-Dyson equations for the nucleon and m...
Bracco, M. E. [UNESP]; Eiras, A. [UNESP]; Krein, G. [UNESP]; Wilets, L.Made available in DSpace on 2022-04-28T19:53:21Z (GMT). No. of bitstreams: 0 Previous issue date: 1994-01-01; The Schwinger-Dyson equations for the nucleon and meson propagators are solved self-consistently in an approximation that goes beyond the Hartree-Fock approximation. The traditional approach consists in solving the nucleon Schwinger-Dyson equation with bare meson propagators and bare meson-nucleon verti...