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Title: Neutrino reaction rates in neutron star matter with ?-isobars


1
Neutrino reaction rates in neutron star matter
with ?-isobars
  • Yanjun Chen
  • Center for Astrophysics
  • University of Science and Technology of China

CSQCDII Beijing China 20th 24th May 2009
2
Composition of neutron stars
  • Nucleons, leptons
  • Hyperons, ?-isobars
  • Pion/Kaon condensation
  • Quarks

3
?-isobars in nuclear matter
  • Properties of ?-isobars
  • 1232 MeV
  • Spin-3/2 and isospin-3/2
  • Belong to the decuplet of group SU(3)
  • Constraints of couplings between ?s and mesons in
    nuclear matter
  • There are no real ?-isobars present at the
    saturation density of nuclear matter and in the
    ground state of finite nuclei
  • The mixed ?-nucleon phase is a metastable state
  • Finite-density QCD sum-rule calculations (Jin,
    Phys.Rev.C,1995)

g?? / g?


g?? / g?
Kosov et al, Phys.Lett.B (1998)
4
Composition of neutron star matter with ?s
T30MeV, neutrino-free case
T30MeV, neutrino-trapped case
Chen et al, Phys.Rev.C, 75, 035806 (2007)
5
Composition of neutron star matter with hyperons
(and ?s)
T0, with hyperons
T0, with hyperons and ?s
Dexheimer Schramm, APJ, 683, 943 (2008)
6
Microphysics of Neutrino reaction rates
Charged current reactions
Neutral current reactions
7
Microphysics of Neutrino scattering rates
G? is the Rarita-Schwinger propagator
Rarita Schwinger, Phys.Rev., 60, 61 (1941)
8
  • Neutral currents
  • constituent quark models
  • Charged currents
  • generalization of con- served vector
    current theory
  • Electromagnetic and weak vector currents
    constitute the octet 8

10 ? 10 64 ? 27 ? 8 ? 1
Chen et al (2009)
9
Neutrino scattering rates
  • Neutral currents
  • Inelastic scattering
  • ? N ? N

? l ? l
? ? ? ?
Chen et al (2007)
10
  • Large vector coupling of ?-
  • CV 2
  • Higher spin of ?s opens additional phase space to
    scatter

Chen et al (2007)
11
Neutrino mean free paths of neutral currents
Chen et al (2007)
12
Neutrino mean free paths of charged currents
  • Charged currents
  • ?e n e- p

?e ?- e- ?
?e ? e- ?
?e N (?) e- ? (N)
Chen et al, Phys. Rev. C, 79, 055802 (2009)
13
Yuan Jeremy, MNRAS, 360, 1493 (2005)
14
Yuan Jeremy, MNRAS, 360, 1493 (2005)
15
Conclusions
  • ?-isobars may exist in neutron star matter.
  • For neutrino opacities in neutron stars, the ?s
    would affect, even be dominant.
  • Proto-neutron stars are a possible site for
    testing ?s by the signals of neutrinos and
    gravitational waves. But it needs further
    studies

16
Thanks !
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