Work

Improved precision calculation of the 0 ν β β contact term within chiral effective field theory

Year: 2025

Type: article

Abstract: Neutrinoless double-beta ( 0 ν β β ) decay is an as-yet unobserved nuclear process, which stands to provide crucial insights for model building beyond the Standard Model of particle physics. Its detection would simultaneously confirm the hypothesis that neutrinos are Majorana fermions, thus violating lepton-number conservation, and provide the first measurement of the absolute neutrino mass scale. This work aims to improve the estimation within chiral effective field theory of the so-called “contact term” for 0 ν β β decay, a short-range two-nucleon effect that is unaccounted for in traditional nuclear approaches to the process. We conduct a thorough review of the justifications for this contact term and the most precise computation of its size to date [ g ν N N = 1.3 ( 6 ) at renormalization point μ = m π ], whose precision is limited by a truncation to elastic intermediate hadronic states. We then perform an extension of this analysis to a subleading class of inelastic intermediate states that we characterize, delivering an updated figure for the contact coefficient [ g ν N N = 1.4 ( 3 ) at μ = m π ] with uncertainty reduced by half. Such nuclear results, especially with enhanced precision, show promise for the resolution of disagreements between estimates of 0 ν ν β β from different many-body methods.

Source: Physical review. D/Physical review. D.

DOI: 10.1103/physrevd.111.055033

Author: Graham Van Goffrier

Institutions: University of Southampton, University College London

Language: English

Topic: Neutrino Physics Research

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Funders: University of Southampton, Science and Technology Facilities Council