Search for new physics with allowed and forbidden beta decays

The Standard Model (SM) of particle physics, while a cornerstone of our understanding, exhibits indications of incompleteness. Recent experimental observations spotlight intriguing deviations from the SM, underscoring the pivotal role of nuclear precision studies in advancing our grasp of physics beyond the Standard Model (BSM). At the heart of this endeavor lies the meticulous examination of nuclear phenomena, with β-decays taking center stage, necessitating both rigorous theoretical frameworks and sophisticated few- and many-body nuclear structure calculations.

In this presentation, I will delve into the quest for exotic weak interactions revealed through β-decays, introducing a comprehensive framework anchored in nuclear structure calculations. This framework is meticulously designed to meet the stringent demands of precision theory requisite for β-decay experiments. Despite the complexity inherent in nuclear structure calculations, our innovative approach facilitates rigorous and controlled precision computations of β-decay observables, aligning seamlessly with the requirements of contemporary experiments.

A focal point of the discussion will be recent advancements concerning BSM tensor interactions, drawing insights from β-decay measurements in 6He and 23Ne. Through the integration of the presented framework with state-of-the-art ab initio No-Core Shell Model (NCSM) calculations, we unveil fresh insights into these intriguing interactions. Furthermore, the presentation will elucidate how this robust framework paves the way for innovative measurements, with a particular emphasis on unique first forbidden β-decays. I will showcase preliminary predictions derived from advanced ab initio NCSM calculations of the forbidden decay of 16N, highlighting the potential impact and efficacy of upcoming experiments.