Study of Neutrino Processes in Astrophysics

1. 恒星内部的中微子过程对以下几个过程的中微子能量损失率进行了深入的研究：(1)等离子体中微子过程，(2)对中微子过程，(3)光子中微子过程，(4)中微子轫致辐射过程，(5)重组中微子过程。在过去的十年中，其中一位作者（Naoki Itoh）和他的合作者使用Weinberg-Salam标准理论对这些中微子过程进行了系统的研究。特别是，在接受本次科学研究资助期间，我们完成了对过去十年中我们在恒星内部中微子过程方面的工作的全面调查。我们还估计了轴向矢量电流在等离子体中微子过程中的贡献。已经发现，与矢量电流的贡献相比，这种贡献几乎可以忽略不计。此外，在计算中微子能量损失率时，还检验了Braaten-Segel近似的准确性。太阳中微子过程我们计算了太阳中微子能量（2mev到20mev）的中微子-氘核截面。数值结果用解析公式进行了拟合。

1. Neutrino Processes in Stellar InteriorsThe neutrino energy loss rate in stellar interiors has been intensively studied for the following neurtino processes : (1) the plasma neutrino process, (2) the pair neutrino process, (3) the photoneutrino process, (4) the neutrino Bremsstrahlung process, and (5) the recombination neutrino process. In the past decade, one of the authors (Naoki Itoh) together with his collaborators has systematically investigated these neutrino processes using the Weinberg-Salam standard theory for the electro-weak interactions. In particular, during the period of receiving the present Grant-in-Aid for Scientific Research, we have accomplished a complete survey of our work in the past decade on the neutrino processes in stellar interiors. We have also estimated the axial vector current contribution in the plasma neutrino process. It has been found that the contribution is almost negligible compared with that from the vector current. Furthermore, accuracy of the Braaten-Segel approximation has been checked in calculating the neutrino energy loss rate.2. Solar Neutrino ProcessesWe have calculated the neutrino-deuteron cross sections for the solar neutrino energies (2 MeV to 20 MeV). The numerical results have been fitted in terms of analytic formulae.