Evidence against manifest right-handed currents in neutron beta decay

TL;DR

This paper reviews experimental bounds on manifest right-handed currents in neutron beta decay, finding that current data strongly constrain their possible mixing angles and mass eigenstates, conflicting with previous lower bounds.

Contribution

It provides updated, stringent limits on right-handed currents in neutron beta decay assuming CKM unitarity, challenging prior bounds on the mass of new particles.

Findings

Stringent limits on mixing angle: -0.00077 to 0.00089

Mass eigenstate bounds: 291.4 to 439.9 GeV

Contradicts established lower bounds on M_2

Abstract

Bounds and presence of manifest right handed currents in neutron beta decay are reviewed. Assuming the unitarity of the Cabibbo-Kobayashi-Maskawa matrix, current experimental situation imposes very stringent limits on the mixing angle, $-0.00077<\zeta<0.00089$, and on the mass eigenstate, $M_2({\rm GeV})\in(291.4,439.9)$, in contradiction with the established lower bound on $M_2$.