*A study of screening effect with Magnetic field*

**Speaker:** Yudong Luo (Univ. of Tokyo, Student talk)

**Abstract: **

In this talk, I will show some result of our exploration screening effects arising from a relativistic magnetized plasma with applications to different nuclear astrophysical site. The electron screening is the reduction of Coulomb potential on the electron cloud, since electrons and positrons will occupy certain Landau levels rather than the continuous momentum phase, the standard treatment of screening potential is not suitable within a background magnetic field. We investigated both the weak screening and strong screening correction on the electron capture rate. Taking into account the correction in Big Bang nucleosynthesis (BBN) arising from a homogeneous primordial magnetic field (PMF), we constrain the epoch at which the PMF was generated and its strength during BBN. Considering such screening corrections to the electron capture rates and using up-to-date observations of primordial elemental abundances. On the other hand, in the explosive nucleosynthesis site, i.e., MHD-Jet Supernovae. The nucleosynthesis in MHD-Jet SNe normally taken as independent from the magnetic field strength, but the reality is, for such high density plasma, electrons and positions are almost in the degenerate state, the Fermi energy highly depends on the magnetic field strength. Therefore, at high temperature region, where the nuclei statistical equilibrium still maintains, one can expect that the electron fraction Y_{e}, which is determined by the electron capture reaction rate, also the key parameter to determine the final r-process nucleosynthesis yields, should be reconsidered.