# Neutrino reaction rates in neutron star matter with

- Slides: 16

Neutrino reaction rates in neutron star matter with isobars Yanjun Chen Center for Astrophysics University of Science and Technology of China CSQCDII Beijing China 20 th – 24 th May 2009 1

Composition of neutron stars l Nucleons, leptons l Hyperons, -isobars l Pion/Kaon condensation l Quarks 2

-isobars in nuclear matter Properties of -isobars – ~ 1232 Me. V – Spin-3/2 and isospin-3/2 – Belong to the decuplet of group Constraints of couplings between s and mesons in nuclear matter ■ l ■ SU(3) g / g l – There are no real -isobars present at the saturation density of nuclear g / g matter and in the ground state of finite nuclei Kosov et al, Phys. Lett. B (1998) – The mixed -nucleon phase is a metastable state – Finite-density QCD sum-rule calculations (Jin, Phys. Rev. C, 1995) 3

Composition of neutron star matter with s T=30 Me. V, neutrino-free case T=30 Me. V, neutrino-trapped case 4 Chen et al, Phys. Rev. C, 75, 035806 (2007)

Composition of neutron star matter with hyperons (and s) T=0, with hyperons and s Dexheimer & Schramm, APJ, 683, 943 (2008) 5

Microphysics of Neutrino reaction rates Neutral current reactions Charged current reactions 6

Microphysics of Neutrino scattering rates E ’ p+q E p E E ’ G is the Rarita-Schwinger propagator Rarita & Schwinger, Phys. Rev. , 60, 61 (1941) 7

l Neutral currents: constituent quark models l Charged currents: generalization of conserved vector current theory – Electromagnetic and weak vector currents constitute the octet [8] [10] [10*] = [64] [27] [8] [1] Chen et al (2009) 8

Neutrino scattering rates l Neutral currents: – Inelastic scattering +N +l + Chen et al 9

l Large vector coupling of – |CV| ~ 2 l Higher spin of s opens additional phase space to scatter Chen et al 10

Neutrino mean free paths of neutral currents Chen et al (2007) 11

Neutrino mean free paths of charged currents l Charged currents: e- + p e + n e + - e- + + e + + e- + ++ e + N ( ) e- + (N) Chen et al, Phys. Rev. C, 79, 055802 (2009) 12

Yuan & Jeremy, MNRAS, 360, 1493 (2005) 13

Yuan & Jeremy, MNRAS, 360, 1493 (2005) 14

Conclusions l -isobars may exist in neutron star matter. l For neutrino opacities in neutron stars, the s would affect, even be dominant. l Proto-neutron stars are a possible site for testing s by the signals of neutrinos and gravitational waves. But it needs further studies… 15

Thanks ! 16