Evidence against manifest right-handed currents in neutron beta decay

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, $M_2({\rm GeV})\in(291.4,439.9)$,incontradictionwiththeestablishedlowerboundon$M_2$.