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Title: Neutrino mean free path in neutron star matter with {delta} isobars

Abstract

The {delta}-isobar degrees of freedom are taken into account in neutron star matter and their contributions to neutrino mean free paths are evaluated. It is found that the charged-current contributions are comparable to those from the neutral-current reactions. The contributions of {delta}-isobars may be a leading sector of neutrino opacities in neutron star matter, but the effects of the process in which the baryon transforms between nucleon and {delta} are unimportant.

Authors:
; ;  [1];  [2];  [3]
  1. Center for Astrophysics, University of Science and Technology of China, Hefei, Anhui 230026 (China)
  2. (China)
  3. (China) and Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou Beijing 730000 (China)
Publication Date:
OSTI Identifier:
21293736
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 79; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevC.79.055802; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CHARGED CURRENTS; DEGREES OF FREEDOM; MEAN FREE PATH; NEUTRAL CURRENTS; NEUTRINOS; NEUTRON STARS; NUCLEONS; OPACITY

Citation Formats

Chen Yanjun, Yuan Yefei, Liu Yuxin, Department of Physics, Peking University, Beijing 100871, and MOE Laboratory of Heavy Ion Physics, Peking University, Beijing 100871. Neutrino mean free path in neutron star matter with {delta} isobars. United States: N. p., 2009. Web. doi:10.1103/PHYSREVC.79.055802.
Chen Yanjun, Yuan Yefei, Liu Yuxin, Department of Physics, Peking University, Beijing 100871, & MOE Laboratory of Heavy Ion Physics, Peking University, Beijing 100871. Neutrino mean free path in neutron star matter with {delta} isobars. United States. doi:10.1103/PHYSREVC.79.055802.
Chen Yanjun, Yuan Yefei, Liu Yuxin, Department of Physics, Peking University, Beijing 100871, and MOE Laboratory of Heavy Ion Physics, Peking University, Beijing 100871. 2009. "Neutrino mean free path in neutron star matter with {delta} isobars". United States. doi:10.1103/PHYSREVC.79.055802.
@article{osti_21293736,
title = {Neutrino mean free path in neutron star matter with {delta} isobars},
author = {Chen Yanjun and Yuan Yefei and Liu Yuxin and Department of Physics, Peking University, Beijing 100871 and MOE Laboratory of Heavy Ion Physics, Peking University, Beijing 100871},
abstractNote = {The {delta}-isobar degrees of freedom are taken into account in neutron star matter and their contributions to neutrino mean free paths are evaluated. It is found that the charged-current contributions are comparable to those from the neutral-current reactions. The contributions of {delta}-isobars may be a leading sector of neutrino opacities in neutron star matter, but the effects of the process in which the baryon transforms between nucleon and {delta} are unimportant.},
doi = {10.1103/PHYSREVC.79.055802},
journal = {Physical Review. C, Nuclear Physics},
number = 5,
volume = 79,
place = {United States},
year = 2009,
month = 5
}
  • We take the {delta}-isobar degrees of freedom into account in neutron star matter and evaluate their contributions to neutrino scattering cross sections and mean free paths. The neutron star matter is described by means of an effective hadronic model in the relativistic mean-field approximation. It is found that {delta} isobars may be present in neutron stars. The electron chemical potential does not decrease and the neutrino abundance does not increase with the increase of the density when neutrinos are trapped in the matter with {delta} isobars. The large vector coupling constant between the {delta}{sup -} and neutrino and the highmore » spin of the {delta} influence significantly the neutrino scattering cross section and lead the contribution of the {delta}{sup -} to the dominance of the scattering rates. In neutrino-trapped case, the presence of {delta}s causes the neutrino mean free path to decrease drastically compared to that in the matter in which baryons are only nucleons.« less
  • The equation of state (EOS) of dense matter and neutrino mean free path (NMFP) in a neutron star have been studied by using relativistic mean field models motivated by effective field theory. It is found that the models predict too large proton fractions, although one of the models (G2) predicts an acceptable EOS. This is caused by the isovector terms. Except G2, the other two models predict anomalous NMFP's. In order to minimize the anomaly, besides an acceptable EOS, a large M* is favorable. A model with large M* retains the regularity in the NMFP even for a small neutronmore » fraction.« less
  • We calculate the neutrino mean free path for neutrino-nucleon scattering in highly asymmetric nuclear matter ({ital N}{gt}{ital Z}) at densities typical for the core of a neutron star. Nuclear matter is described by means of a relativistic field theory of nucleons coupled to neutral, scalar ({sigma}), and vector ({omega}) mesons and to charged vector mesons ({ital d}). The correlation effects induced by the strong interaction of nucleons are taken into account within a self-consistent mean field approximation. The contribution of the exchange terms to the nucleon-nucleon interaction is also included. We present results for physical situations which are expected tomore » occur in the cooling of neutron stars. Exchange terms have the effect of increasing the neutrino mean free path by about 50{percent}. {copyright} {ital 1996 The American Physical Society.}« less
  • We study dense hadronic matter in a generalized relativistic mean field approach which contains nonlinear couplings of the {sigma}, {omega}, {rho}, {delta} fields and compare its predictions for properties of neutron stars with the corresponding results from different models found in the literature. Our predictions indicate a substantial modification in static global properties of nuclear matter and neutron stars with the inclusion of the {delta} meson into the formalism.
  • We calculate asymmetric neutrino absorption and scattering cross sections on hot and dense magnetized neutron star matter, including hyperons in fully relativistic mean-field theory. The absorption/scattering cross sections are suppressed/enhanced incoherently in the direction of the magnetic field B=Bz-circumflex. The asymmetry is 2-4% at the matter density {rho}{sub 0{<=}{rho}B{<=}}3{rho}{sub 0} and temperature T{<=}40 MeV for B=2x10{sup 17} G. This asymmetry is comparable to the effects owing to parity violation or asymmetric magnetic field topology proposed for the origin of pulsar kicks.