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Neutrino Reactions on the Deuteron in Core-Collapse Supernovae

Neutrino Reactions on the Deuteron in Core-Collapse Supernovae . arXiv: 1402.0959, PRC 80, 035802 (2009 ). Satoshi Nakamura Osaka University. Collaborators: S. Nasu , T. Sato (Osaka U.), K. Sumiyoshi (Numazu Coll. Tech.)

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Neutrino Reactions on the Deuteron in Core-Collapse Supernovae

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  1. Neutrino Reactions on the Deuteron in Core-Collapse Supernovae arXiv:1402.0959, PRC 80, 035802 (2009) Satoshi Nakamura Osaka University Collaborators: S. Nasu, T. Sato (Osaka U.), K. Sumiyoshi (Numazu Coll. Tech.) F. Myhrer, K. Kubodera (U. of South Carolina)

  2. Introduction Neutrino reactions on the deuteron Important relevance to neutrino physics, astrophysics • Supernova (n-heating, n-emission) • n-oscillation experiment @ SNO • Solar fusion (pp-chain)

  3. Calculational method Well-established method for electroweak processes in few-nucleon systems AV18, Nijmegen, Bonn, etc.

  4. Contents • Model for Hew • n-heatingin supernova • n-emission in supernova

  5. MODEL

  6. Nuclear current

  7. Impulse approximation (IA) current

  8. Exchange axial-vector current

  9. Most recent applications of the model to weak processes ★pp-fusion ( ) for solar model , Schiavilla et al. PRC 58 (1998) • ★Muon capture ( , ) , Marcucciet al., PRC 83 (2011) • [1] [2] TheoryMuSun@PSI • [3] Theory [1] Cargnelli et al. (1998) [2] Bardin et al. NPA 453 (1986) [3] Ackerbauer et al. PLB 417 (1998) • nd-reactions ( , ) for SNO experiment • SN et al. PRC 63 (2000) ; NPA707 (2002) •  evidence ofn-oscillation, solar nproblem resolved

  10. Neutrino-deuteron reaction as heating mechanism in Supernova In many simulations, supernova doesn’t explode ! extra assistance needed for re-accelerating shock-wave ★neutrino absorption on nucleon (main) ★neutrino scattering or absorption on nuclei (extra agent) SXN, K. Sumiyoshi, T. Sato, PRC 80, 035802 (2009)

  11. Abundance of light elements in supernova Sumiyoshi, Röpke, PRC 77, 055804 (2008) 15 M, 150ms after core bounce Nuclear statistical equilibrium assumed cf. Arcones et al. PRC 78, 015806 (2008)

  12. Energy transfer cross section CC (absorption) NC (scattering) Thermal average

  13. Result Neutrino-deuteron cross sections

  14. Thermal average of energy transfer cross sections _ 3H (n) : Arcones et al. PRC 78 (2008) 4He(n) : Haxton PRL 60 (1998) 3He (n): O’conner et al. PRC 78 (2007) 4He (n) : Gazit et al. PRL 98 (2007)

  15. Thermal average of energy transfer cross sections

  16. Electron capture on deuteron & NN fusion as neutrino emission mechanism S. Nasu, SXN, T. Sato, K. Sumiyoshi, F. Myrer, K. Kubodera arXiv:1402.0959

  17. n-emission previously considered (A≤2) New agents

  18. Emissivity (Q)

  19. Emissivity (Q) 11 dimensional integral !! Approximation necessary to evaluate Q

  20. Emissivity (Q) Approximation ! 3 dimensional integral

  21. Previous common approximation to evaluate QNN-brem • One-pion-exchange potential, Born approximation Low-energy theorem • Neglect momentum transfer ( ) •  also angular correlation between n and n • Nuclear matrix element  long wave length limit  constant _

  22. Supernova profile Sumiyoshi, Röpke, PRC 77, 055804 (2008) 150 ms after core bounce Nuclear statistical equilibrium assumed

  23. Result • Surface region of proto-neutron star • Inner region of proto-neutron star • Deuteron can be largely modified, or even doesn’t exist • ”deuteron” as two-nucleon correlation in matter • More elaborate approach based on thermodynamic Green’s function • (S. Nasu, PhD work in progress)

  24. ne-emissivity electron capture NN fusion Deuterons exit at the cost of the proton abundance + s(e- p) > s(e- d)  Effectively reduced neemissivity less n-flux, n-heating, slower deleptonization & evolution of proto-neutron star  Need careful estimate of light element abundance & emissivity e-p, e+e-: Bruenn, ApJS 58 (1985) NN brem: Frimanet al, ApJ 232 (1979) Q (e- p) > Q(e- d) > Q (NNd)

  25. _ ne-emissivity positron capture NN fusion Q (e+n) > Q(e+ d) > Q (NNd)

  26. Change of ne emissivity due to deuteron Q(N+d) / Q(N) Mass fraction _ ne p (w.o. d fraction) p ne d Deuterons exit at the cost of the proton abundance + s(e- p) > s(e- d)  Effectively reduced neemissivity

  27. _ (inner region proto-neutron star) ne-emissivity NN brems e+e- _ npdne necan be very important !

  28. nm-emissivity Q (NN brem) ≈ Q (npd) Whenever NN brem is important, npdcan be also important  Possible important role in proto-neutron star cooling

  29. Meson exchange current effect on Q Large effect on NN fusion !

  30. Why so large meson exchange current effect ? • Higher NN kinetic energy causes large exchange current effect • Axial exchange current & higher partial waves are important ; uncertainty

  31. Summary Deuteron breakup (n-heating) & formation (n-emission) in SN Framework : NN wave functions based on high-precision NN potential + 1 & 2-body nuclear weak currents (tested by data) n-heating: Substantial abundance of light elements (NSE model) for deuteron : much larger than those for 3H, 3He, 4He 25-44% of for the nucleon

  32. Summary n-emission: New agents other than direct & modified Urca, NN bremsstrahlung Emissivities Rigorous evaluation of nuclear matrix elements No long wave length limit, no Born approximation Electron captures  effectively reduced ne emissivity Need careful estimate of light element abundance & emissivity _ _ NN fusions npdnncan be very important for ne & nmemissivites  play a role comparable to NN bremsstrahlung & modified Urca

  33. Future work • Similar calculations of emissivites for modified Urca • NN bremsstrahlung • rigorous few-body calculation is still lacking SN et al. in progress • Elaborate treatment for nuclear medium effects • Thermodynamic Green’s function approach (S. Nasu, PhD work in progress)  Useful information for supernova and neutron star cooling simulations

  34. Backups

  35. Emissivites from direct Urca, e+e- annihilation, NNbremscompilation I Emissivites from election captures on d & NN fusion  compilation II • Compilation I : ShenEoS, N, 4He, a heavy nucleus • Compilation II : light elements abundance from Sumiyoshi & Röpke (2008) Both have the same density, temperature, electron fraction

  36. Exchange vector current • Current conservation for one-pion-exchange potential • VND coupling is fitted to np dg data

  37. Comparison with np dg data Exchange currents contribute about 10 %

  38. Exchange axial charge Kubodera, Delorme, Rho, PRL 40 (1978) Soft pion theorem + PCAC

  39. r(x) [fm-1] const.

  40. Neutrino spectrum

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