The in-medium effects on the neutrino reaction in dense matter

The nucleon form factors in free space are usually thought to be modified when a nucleon is bound in a nucleus or immersed in a nuclear medium. We investigated effects of the density-dependent axial and weak-vector form factors on the electro-neutrino (νe) and anti-electro-neutrino (νe) reactions with incident energy Ev ≤ 80 MeV via neutral current (NC) and charged current (CC) for a nucleon in a nuclear medium or 12C. For the density-dependent form factors, we exploited the quark-meson-coupling (QMC) model, and apply them to the νe and νe induced reactions by NC and CC. In CC reaction, about 5 % decrease of the electro neutrino (νe) reaction cross section on the nucleon is shown to be occurred in normal density, ρ = ρ0∼0.15fm−3, and also about 5 % reduction of total νe cross section on 12C is obtained by the modification of the weak form factors for bound nucleons. Density effects for both cases are relatively small, but they are as large as the effect by the Coulomb distortion of outgoing leptons in t...