Neutrino-nucleus reactions on $^{16}$O based on new shell-model Hamiltonians

TL;DR

This paper uses new shell-model Hamiltonians to accurately calculate neutrino-induced reactions on $^{16}$O, exploring reaction mechanisms, cross sections, and implications for nucleosynthesis in supernovae.

Contribution

It introduces improved shell-model Hamiltonians for $p$-shell nuclei and applies them to evaluate neutrino reactions and nucleosynthesis effects in supernovae.

Findings

New shell-model Hamiltonians describe $^{16}$O structure well.

Multi-particle emission channels significantly affect nucleosynthesis yields.

Updated cross sections differ from previous CRPA calculations.

Abstract

Neutrino-induced reactions on $^{16}$O are investigated by shell-model calculaions with new shell-model Hamiltonians, which can describe well the structure of $p$-shell and $p$-$sd$ shell nuclei. Distribution of the spin-dipole strengths in $^{16}$O, which give major contributions to the $\nu$-$^{16}$O reaction cross sections, is studied with the new Hamiltonians. Muon-capture reaction rates on $^{16}$O are also studied to discuss the quenching of the axial-vector coupling in nuclear medium. Charged-current and neutral-current reaction cross sections are evaluated in various particle and $\gamma$ emission channels as well as the total ones at neutrino energies up to $E_{\nu}\approx$ 100 MeV. Branching ratios for the various channels are obtained by the Hauser-Feshbach statistical model calculations, and partial cross sections for single- and multi-particle emission channels are evaluated. The cross sections updated are compared with previous continuum random phase approximation (CRPA) calculations. Effects of multi-particle emission channels on nucleosynthesis in core-collapse supernova (SN) explosions are investigated. Inclusion of $\alpha$p emission channels is found to lead to an enhancement of production yields of $^{11}$B and $^{11}$C through $^{16}$O ($\nu$, $\nu$' $\alpha$p) $^{11}$B and $^{16}$O ($\nu$, e$^{-}$ $\alpha$p) $^{11}$C reactions, respectively.