Multipole decomposition of tensor interactions of fermionic probes with composite particles and BSM signatures in nuclear reactions

TL;DR

This paper develops a new mathematical formalism for tensor interactions in nuclear reactions, simplifying the analysis of beyond Standard Model physics in experiments like beta-decay and dark matter detection.

Contribution

It introduces a general tensor nuclear response formalism that unifies BSM and Standard Model operators, reducing computational complexity in reaction analysis.

Findings

New tensor decomposition method for nuclear responses

Application to 6He beta-decay example

Facilitates analysis of BSM physics in nuclear experiments

Abstract

A multipole decomposition of a cross-section is a useful tool to simplify the analysis of reactions due to their symmetry properties. By using a new approach to decompose antisymmetric tensor-type interactions within the multipole analysis, we introduce a general mathematical formalism for working with tensor couplings. This allows us to present a general tensor nuclear response, which is particularly useful for ongoing beta-decay experiments looking for physics beyond the Standard Model, as well as other exotic particle scatterings off nuclei, e.g., in dark matter direct detection experiments. Using this method, beyond the Standard Model operators identify with the known Standard Model operators, eliminating the need for calculations of additional matrix elements. We present in detail BSM expressions useful for beta-decay experiments and give an exemplary application for 6He beta-decay, although the formalism is easily generalizable for calculating other exotic scattering reactions.