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Title: Baryon decuplet in the chiral dynamics of {lambda} hyperons in nuclear matter

Abstract

We study the long range part of the {lambda}-hyperon optical potential in nuclei using quantum many body techniques and flavor-SU(3) chiral Lagrangians as starting point. More precisely, we study the contributions to the {lambda}-hyperon optical potential due to the long-range two-pion exchange, with {sigma} and {sigma}* baryons in the internal baryonic lines and considering Nh and {delta}h excitations. We also consider the contribution to the spin-orbit potentials that comes out from these terms. Our results support a natural explanation of the smallness of the {lambda}-nuclear spin-orbit interaction and show the importance of the {sigma}* and {delta} degrees of freedom for the hyperon-nucleus interactions.

Authors:
;  [1]
  1. Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia CSIC, Institutos de Investigacion de Paterna, Aptdo. 22085, E-46071 Valencia (Spain)
Publication Date:
OSTI Identifier:
20995166
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevC.75.035207; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CHIRALITY; DEGREES OF FREEDOM; EXCITATION; FLAVOR; L-S COUPLING; LAGRANGIAN FUNCTION; MANY-BODY PROBLEM; NUCLEAR MATTER; NUCLEI; NUCLEON-HYPERON INTERACTIONS; PIONS; POTENTIALS; SIGMA MINUS PARTICLES; SPIN

Citation Formats

Camalich, J. Martin, and Vacas, M. J. Vicente. Baryon decuplet in the chiral dynamics of {lambda} hyperons in nuclear matter. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.035207.
Camalich, J. Martin, & Vacas, M. J. Vicente. Baryon decuplet in the chiral dynamics of {lambda} hyperons in nuclear matter. United States. doi:10.1103/PHYSREVC.75.035207.
Camalich, J. Martin, and Vacas, M. J. Vicente. Thu . "Baryon decuplet in the chiral dynamics of {lambda} hyperons in nuclear matter". United States. doi:10.1103/PHYSREVC.75.035207.
@article{osti_20995166,
title = {Baryon decuplet in the chiral dynamics of {lambda} hyperons in nuclear matter},
author = {Camalich, J. Martin and Vacas, M. J. Vicente},
abstractNote = {We study the long range part of the {lambda}-hyperon optical potential in nuclei using quantum many body techniques and flavor-SU(3) chiral Lagrangians as starting point. More precisely, we study the contributions to the {lambda}-hyperon optical potential due to the long-range two-pion exchange, with {sigma} and {sigma}* baryons in the internal baryonic lines and considering Nh and {delta}h excitations. We also consider the contribution to the spin-orbit potentials that comes out from these terms. Our results support a natural explanation of the smallness of the {lambda}-nuclear spin-orbit interaction and show the importance of the {sigma}* and {delta} degrees of freedom for the hyperon-nucleus interactions.},
doi = {10.1103/PHYSREVC.75.035207},
journal = {Physical Review. C, Nuclear Physics},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • The chiral quark model gives a reasonably good description of many low-energy observables by incorporating the effective degrees carried by the constituent quarks and Goldstone bosons. We calculate the decuplet to octet transition magnetic moments and the decay widths of several excited hyperons using this model. The various radiative decay widths from the chiral quark roughly agree with experimental data including recent JLAB measurement.
  • We present a novel approach to the density-dependent mean field and the spin-orbit interaction of a {lambda} hyperon in a nuclear many-body system, based on flavor-SU(3) in-medium chiral perturbation theory. The leading long-range {lambda}N interaction arises from kaon exchange and from two-pion exchange with a {sigma} hyperon in the intermediate state. The empirical {lambda}-nucleus potential depth of about -28 MeV is well reproduced with a single cutoff scale, {lambda}=0.7 GeV, effectively representing all short-distance (high-momentum) dynamics not resolved at scales characteristic of the nuclear Fermi momentum. This value of {lambda} is remarkably consistent with the one required to reproduce themore » empirical saturation point of isospin-symmetric nuclear matter in the same framework. The smallness of the {lambda}-nuclear spin-orbit interaction finds a natural (yet novel) explanation in terms of an almost complete cancellation between short-range contributions (properly rescaled from the known nucleonic spin-orbit coupling strength) and long-range terms generated by iterated one pion exchange with intermediate {sigma} hyperons. The small {sigma}{lambda}-mass difference figures prominently in this context.« less
  • The internal structure of the resonant {Lambda}(1405) state is investigated based on meson-baryon coupled-channels chiral dynamics, by evaluating density distributions obtained from the form factors of the {Lambda}(1405) state. The form factors are extracted from current-coupled scattering amplitudes in which the current is coupled to the constituent hadrons inside {Lambda}(1405). Using several probe interactions and channel decomposition, we find that the resonant {Lambda}(1405) state is dominantly composed of widely spread K-bar around N, with a small fraction of the escaping {pi}{Sigma} component.
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