Parity violation in neutron capture on the proton: determining the weak pion-nucleon coupling

TL;DR

This paper uses chiral effective field theory to analyze parity violation in neutron-proton capture, aiming to determine the weak pion-nucleon coupling constant, with results limited by current experimental uncertainties.

Contribution

It provides a novel combined analysis of neutron capture and proton-proton scattering to extract the weak pion-nucleon coupling constant.

Findings

Weak pion-nucleon coupling constant estimated

Uncertainty dominated by experimental error

Analysis framework applicable to other parity violation studies

Abstract

We investigate the parity-violating analyzing power in neutron capture on the proton at thermal energies in the framework of chiral effective field theory. By combining this analysis with a previous analysis of parity violation in proton-proton scattering, we are able to extract the size of the weak pion-nucleon coupling constant. The uncertainty is significant and dominated by the experimental error which is expected to be reduced soon.