Speaker
Description
The nucleon axial coupling, $g_A$, is ubiquitous in nuclear physics. It also plays an important role in our understanding of thee first row of the CKM Matrix and the search for new physics. With lattice QCD, we have a theoretical determination of $g_A$ with a $1%$ uncertainty, which already places the most stringent constraint on right-handed BSM currents. A theoretical uncertainty of $0.2%$ would allow for a theoretical prediction of the neutron lifetime with an uncertainty matching the size of the uncertainty on the lifetime measurements that currently leads to a $4\sigma$ discrepancy between the beam and bottle experiments. At $0.4%$, there are newly (re?) discovered QED corrections which become relevant for extracting the QCD value of $g_A$ from the experimental measurements. I will discuss the current status of lattice QCD determinations of $g_A$, ongoing calculations, and prospects for incorporating these electromagnetic corrections and aiming for a theoretical uncertainty of $0.2%$.
