# Simultaneous Measurements of the Beta Neutrino Angular Correlation in $^{32}$Ar Pure Fermi and Pure Gamow-Teller Transitions using Beta-Proton Coincidences

## TL;DR

This study measures the beta-neutrino angular correlation in $^{32}$Ar decay using beta-proton coincidences, confirming Standard Model predictions and demonstrating potential for high-precision tests of weak interactions.

## Contribution

First simultaneous measurement of beta-neutrino angular correlation in pure Fermi and Gamow-Teller transitions using proton energy shifts in $^{32}$Ar decay.

## Key findings

- Results agree with Standard Model predictions.
- Future experiments can achieve 10$^{-3}$ precision.
- Provides constraints on scalar and tensor weak interactions.

## Abstract

We report first time measurements of the beta-neutrino angular correlation based on the kinetic energy shift of protons emitted in parallel or anti-parallel directions with respect to the positron in the beta decay of $^{32}$Ar. This proof of principle experiment provided simultaneous measurements for the superallowed 0$^+$~$\rightarrow$~0$^+$ transition followed by a 3356~keV proton emission and for a Gamow-Teller transition followed by a 2123~keV proton emission. The results, respectively ${\tilde a_{\beta\nu}}=1.01(3)_{(stat)}(2)_{(syst)}$ and ${\tilde a_{\beta\nu}}=-0.22(9)_{(stat)}(2)_{(syst)}$, are found in agreement with the Standard Model. A careful analysis of the data shows that future measurements can reach a precision level of 10$^{-3}$ for both pure Fermi and pure Gamow-Teller decay channels, providing new constraints on both scalar and tensor weak interactions.