Dispersion relation analysis of the radiative corrections to g A in the neutron β-decay

Abstract

Abstract We present the first and complete dispersion relation analysis of the inner radiative corrections to the axial coupling constant g A in the neutron β-decay. Using experimental inputs from the elastic form factors and the spin-dependent structure function g 1, we determine the contribution from the γW-box diagram to a precision better than 10 −4. Our calculation indicates that the inner radiative corrections to the Fermi and the Gamow-Teller matrix element in the neutron β-decay are almost identical, i.e. the ratio λ = g A /g V is almost unrenormalized. With this result, we predict the bare axial coupling constant to be g ∘ A = − 1.2754 13 exp 2 RC $$ {\overset{\circ }{g}}_A=-1.2754{(13)}_{\mathrm{exp}}{(2)}_{\mathrm{RC}} $$ based on the PDG average λ = −1.2756(13).

Keywords

• Quark Masses and SM Parameters
• Neutrino Physics