Abstract
We evaluate the Fermi and Gamow-Teller (GT) matrix elements in tritium decay by including in the charge-changing weak current the corrections up to one loop recently derived in nuclear chiral effective field theory (). The trinucleon wave functions are obtained from hyperspherical-harmonics solutions of the Schrödinger equation with two- and three-nucleon potentials corresponding to either (the N3LO/N2LO combination) or meson-exchange phenomenology (the AV18/UIX combination). We find that contributions due to loop corrections in the axial current are, in relative terms, as large as (and in some cases, dominate) those from one-pion exchange, which nominally occur at lower order in the power counting. We also provide values for the low-energy constants multiplying the contact axial current and three-nucleon potential, required to reproduce the experimental GT matrix element and trinucleon binding energies in the N3LO/N2LO and AV18/UIX calculations.
- Received 5 May 2016
- Revised 12 July 2016
DOI:https://doi.org/10.1103/PhysRevC.94.024003
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