Beta asymmetry parameter in the decay of 114In

TL;DR

This paper reports the most precise measurement of the beta asymmetry parameter in the decay of 114In, confirming Standard Model predictions and setting new limits on tensor currents using advanced simulation techniques.

Contribution

The study introduces a combined experimental and GEANT4 simulation approach to accurately measure the beta asymmetry parameter in 114In decay, addressing scattering and magnetic field effects for the first time.

Findings

Measured A = -0.994 +/- 0.014, the most accurate to date.

Results agree with Standard Model prediction of A = -1.

Provides new constraints on tensor charged weak currents.

Abstract

The beta asymmetry parameter A for the pure Gamow-Teller decay of 114In is reported. The low temperature nuclear orientation method was combined with a GEANT4 based simulation code allowing for the first time to address in detail the effects of scattering and of the magnetic field. The result, A = -0.994 +/- 0.010stat +/- 0.010syst, constitutes the most accurate value for the asymmetry parameter of a nuclear beta transition to date. The value is in agreement with the Standard Model prediction of A = -1 and provides new limits on tensor type charged weak currents.