Structure of the correlation coefficients S (Ee) and U (Ee) of the neutron β decay

In the standard effective V −A theory of low-energy weak interactions [i.e., in the standard model (SM)] we analyze the structure of the correlation coefficients S (E_e) and U (E_e) , where E_e is the electron energy. These correlation coefficients were introduced to the electron-energy and angular distribution of the neutron beta decay by Ebel and Feldman [Nucl. Phys. 4, 213 (1957), 10.1016/0029-5582(87)90020-4] in addition to the set of correlation coefficients proposed by Jackson et al. [Phys. Rev. 106, 517 (1957), 10.1103/PhysRev.106.517]. The correlation coefficients S (E_e) and U (E_e) are induced by simultaneous correlations of the neutron and electron spins and electron and antineutrino three-momenta. These correlation structures do no violate discrete P, C, and T symmetries. We analyze the contributions of the radiative corrections of order O (α /π ) , taken to leading order in the large nucleon mass m_N expansion, and corrections of order O (E_e/m_N) , caused by weak magnetism and proton recoil. In addition to the radiative O (α /π ) and O (E_e/m_N) corrections we take into account the contributions of the second class currents by Weinberg [Phys. Rev. 112, 1375 (1958), 10.1103/PhysRev.112.1375]. The contributions of interactions beyond the SM (BSM) are calculated in terms of the phenomenological coupling constants of BSM interactions by Lee and Yang [Phys. Rev. 104, 254 (1956), 10.1103/PhysRev.104.254].