Muon capture on light nuclei

We review the latest theoretical predictions for the muon capture reactions 2H(μ-,νμ)nn and 3He(μ-,νμ)3H, obtained using a realistic model for the nuclear Hamiltonian and weak transition operator, derived either in a meson-exchange or in a chiral effective field theory (χEFT) framework. The total rates are found to be 392.0 ± 2.3 s1 for A = 2, and 1484 ± 13 s-1 for A = 3, where the spread accounts for the model dependence and cutoff sensitivity in the χEFT currents. The contributions of the two-body axial currents, obtained imposing the partially-conserved-axial-current hypothesis at the two-body level, investigated in the χEFT framework, are found to be negligible. The first steps toward a fully consistent χEFT calculation are also discussed.