Muon capture on light nuclei

TL;DR

This paper calculates muon capture rates on light nuclei, specifically deuterium and helium-3, using chiral effective field theory and realistic nuclear potentials, providing precise theoretical predictions.

Contribution

It introduces a detailed calculation of muon capture on light nuclei incorporating axial two-body currents constrained by the PCAC hypothesis and chiral EFT, with improved accuracy.

Findings

Capture rate for deuterium: 393.1(8) s^{-1}

Capture rate for helium-3: 1488(9) s^{-1}

Uncertainties mainly from fitting procedures

Abstract

This work investigates the muon capture reactions 2H(\mu^-,\nu_\mu)nn and 3He(\mu^-,\nu_\mu)3H and the contribution to their total capture rates arising from the axial two-body currents obtained imposing the partially-conserved-axial-current (PCAC) hypothesis. The initial and final A=2 and 3 nuclear wave functions are obtained from the Argonne v_{18} two-nucleon potential, in combination with the Urbana IX three-nucleon potential in the case of A=3. The weak current consists of vector and axial components derived in chiral effective field theory. The low-energy constant entering the vector (axial) component is determined by reproducting the isovector combination of the trinucleon magnetic moment (Gamow-Teller matrix element of tritium beta-decay). The total capture rates are 393.1(8) s^{-1} for A=2 and 1488(9) s^{-1} for A=3, where the uncertainties arise from the adopted fitting procedure.