Theoretical description of the neutron beta decay in the standard model at the level of 10 − 5

In the framework of the Standard Model (SM) a theoretical description of the neutron beta decay is given at the level of 10−5. The neutron lifetime and correlation coefficients of the neutron beta decay for a polarized neutron, a polarized electron, and an unpolarized proton are calculated at the account for (i) the radiative corrections (RC) of order O (αEe/mN) ∼ 10−5 , i.e., O (αEe/mN) RC, to Sirlin's outer and inner O (α/π) RC, where α and Ee are the fine-structure constant and the electron energy, respectively; (ii) the outer O (αEe/mN) RC, caused by Sirlin's outer O (α/π) RC and the phase-volume of the neutron beta decay, calculated to next-to-leading order in the large nucleon mass m N expansion; (iii) the corrections of order O (E2e/m2N) ∼10−5, caused by weak magnetism and proton recoil; and (iv) Wilkinson's corrections of order 10−5 [Wilkinson, Nucl. Phys. A377, 474 (1982)]. These corrections define the SM background of the theoretical description of the neutron beta decay at the level of 10−5, which is required by experimental searches of interactions beyond the SM with experimental uncertainties of a few parts of 10−5.