Precision analysis of pseudoscalar interactions in neutron beta decays

Abstract

We analyze the contributions of the one–pion–pole (OPP) exchange, caused by strong low–energy interactions, and the pseudoscalar interaction beyond the Standard Model (BSM) to the correlation coefficients of the neutron β−–decays for polarized neutrons, polarized electrons and unpolarized protons. The strength of contributions of pseudoscalar interactions is defined by the effective coupling constant Cps=Cps(OPP)+Cps(BSM). We show that the contribution of the OPP exchange is of order Cps(OPP)∼−10−5. The effective coupling constant Cps(BSM) of the pseudoscalar interaction BSM can be in principle complex. Using the results, obtained by González-Alonso et al. (2019) [34] we find that the values of the real and imaginary parts of the effective coupling constant Cps(BSM) are constrained by −3.5×10−5<ReCps(BSM)<0 and ImCps(BSM)<−2.3×10−5, respectively. The obtained results can be used as a theoretical background for experimental searches of contributions of interactions BSM in asymmetries of the neutron β−–decays with a polarized neutron, a polarized electron and an unpolarized proton at the level of accuracy of a few parts of 10−5 or even better Abele (2016) [40].