Journal of High Energy Physics (Feb 2024)

Constraints on subleading interactions in beta decay Lagrangian

  • Adam Falkowski,
  • Martín González-Alonso,
  • Ajdin Palavrić,
  • Antonio Rodríguez-Sánchez

DOI
https://doi.org/10.1007/JHEP02(2024)091
Journal volume & issue
Vol. 2024, no. 2
pp. 1 – 54

Abstract

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Abstract We discuss the effective field theory (EFT) for nuclear beta decay. The general quark-level EFT describing charged-current interactions between quarks and leptons is matched to the nucleon-level non-relativistic EFT at the O MeV $$ \mathcal{O}\left(\textrm{MeV}\right) $$ momentum scale characteristic for beta transitions. The matching takes into account, for the first time, the effect of all possible beyond-the-Standard-Model interactions at the subleading order in the recoil momentum. We calculate the impact of all the Wilson coefficients of the leading and subleading EFT Lagrangian on the differential decay width in allowed beta transitions. As an example application, we show how the existing experimental data constrain the subleading Wilson coefficients corresponding to pseudoscalar, weak magnetism, and induced tensor interactions. The data display a 3.5 sigma evidence for nucleon weak magnetism, in agreement with the theory prediction based on isospin symmetry.

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