Neutrino Capture Reactions on ${}^{40}$Ar

Gamow-Teller (GT) strength in ${}^{40}$Ar is studied by shell-model calculations with monopole-based universal intearction, which has tensor components of $\pi$\rho$-meson exchanges. Calculated GT strength is found to be consistent with the experimental data obtained by recent ($p,n$) reactions. Neutrino capture cross sections on ${}^{40}$Ar for solar neutrinos from ${}^8$B are found to be enhanced compared with previous calculations. The reaction cross sections for multipoles other than $0^{+}$ and $1^{+}$ are obtained by random-phase approximation (RPA). Their contributions become important for neutrino energies larger than 50 MeV.