Quark mass difference effects in hadronic Fermi matrix elements from first principles

Abstract

It was recently estimated that the strong isospin-symmetry breaking (ISB) corrections to the Fermi matrix element in free neutron decay could be of the order $10^{-4}$, one order of magnitude larger than the na\"ıve estimate based on the Behrends-Sirlin-Ademollo-Gatto theorem. To investigate this claim, we derive a general expression of the leading ISB correction to hadronic Fermi matrix elements, which takes the form of a four-point correlation function in lattice gauge theory and is straightforward to compute from first principles. Our formalism paves the way for the first determination of such correction in the neutron sector with fully-controlled theory uncertainties.

Version accepted by PLB

References in corpus (4)

• Ab initio calculation of the neutron-proton mass difference
• Lattice QCD at the physical point: light quark masses
• Light quark masses in N_f = 2+1 lattice QCD with Wilson fermions
• Fermi matrix element with isospin breaking

Cited by in corpus (5)

• The Standard Model theory of neutron beta decay
• Opportunities and open questions in modern $\beta$ decay
• Effect of isoscalar and isovector scalar fields on baryon semileptonic decays in nuclear matter
• Most general neutron decay correlations: Standard Model recoil and radiative corrections
• Testing effective field theory with the most general neutron decay correlations