Neutrino reactions on two-nucleon system and core-

collapse supernova

Shota Nasu(Osaka.U)

Collaborators:

T. Sato (Osaka.U),K. Sumiyoshi(Numazu Coll.Tech.),S. Nakamura (JLab),F. Myhrer (USC),K.Kubodera (USC)

Introduction: neutrino reactions in core-collapse supernovae

Electron captures Elastic scattering Pair creation and annihilation Nucleon Bremsstrahlung

S. Bruenn (1985)

Absorption, production and scattering reactions

K. Sumiyoshi and G. Röpke, (2008)

Existence of light elements (d,t,3He) A. Arcones et al. (2008)

: E. O’Connor et al., (2007), A. Arcones et al., (2008)

: S. X. Nakamura et al.(2009)

Neutrino absorption reaction in light elements ( for heating )

Neutrino absorption: heating mechanism (shock wave revival -> delayed explosion)

production: cooling mechanism (proto-neutron star to neutron star, source of neutrinos)

In this work: neutrino production reaction in two-nucleon system (for cooling)

Motivation: Neutrino production in two nucleon collision

Modified URCA processes :

Neutrino bremsstrahlung :

Friman and Maxwell (1979) One-pion-exchangeHanhalt et al.(2001) Low Energy Theorem

Objective : Analysis of neutrino production reactions on two-nucleon system for SN simulations

deuteron in final state : EFT: deuteron as dibaryon Ando, Kubodera (2006)

Those works can be used only low energy region.

Today’s talk : process

Crucial for cooling mechanism

Formalism

Weak Hamiltonian:

Nuclear currents:

Standard Nuclear Physics Approach (SNPA)

model of nuclear current used to analyze nu-d for SNO data

exchange currents + excited exchange currents

Neutrino emissivity

: Fermi-Dirac distribution function

S.W.Bruenn(1985)T.A.Thompson et al.(2000)　 etc.

: emitted neutrino energy

Charged current process

: n-n kinetic energy

non-degenerate limit

→ keep only dominant 1S0(nn) -> 3S1(d) Gamov-Teller transition

Energy dependence of

: Neutron density

Strong E-dependence of |M| large 1S0 scattering length

emissivity

for nucleon

for lepton

Examine the simple case

The facter enhances the high energy contribution

Even at low temperature..

T.A.Thompson et al. (2000) etc.

Full result of emissivity

IA+EXC nuclear currents,Including higher partial waves

OPE model, approx. E-independent |M|

Summary

Analysis of neutrino emissivity

near future plan

・ examine validity of using low energy approximation

・ complete table of whole reactions rates including electron capture

d

shock position

t

150ms after core bounce

: neutron mass fraction: mass density in units of

B: deuteron binding energy