In-medium effect with muon-neutrino and anti-muon-neutrino quasi-elastic scattering from C-12 nucleons

Abstract

We investigated the in-medium effect by density-dependent axial and weak-vector form factors on muon-neutrino (nu(mu)) and anti-muon-neutrino ((nu(mu)) over bar) scattering in the quasi-elastic (QE) region from nucleons (N*) bound in a nucleus or immersed in a nuclear medium via neutral current (NC) and charged current (CC). For the density-dependent form factors, we exploited a quark-meson-coupling (QMC) model. We found that the nu(mu)((nu) over bar (mu))-N* scattering cross sections via NC in the QE region usually decrease with an increased medium density, while those using CC were increased. However, their rate of change was sensitive to the four-momentum transfer given to a bound nucleon through scattering. We compared these results obtained by the elementary process corrected by the in-medium effect to the BNL and MiniBooNE data, which measured nu(mu) scattering cross sections per nucleon through nu(mu) - C-12 scattering in C-12 composite targets. The incident energy range was 550 < E-nu < 3000 MeV. We increased the energy up to 100 GeV to compare our results to the NOMAD experimental data. In order to study the density effects on a nucleon embedded in C-12, we exploited the QMC form factors evaluated at rho = 0.5 rho(0), where the normal density rho(0) similar to 0.15 fm(-3). The strangeness contributions in NC scattering are also incorporated into the form factors for comparison with experimental data. Our numerical results show that most of the experimental data can be explained in a satisfactory manner by the density-dependent elementary process, but there are some remaining deviations resulting from the nuclear structure, particularly in the low and high momentum-transfer regions.