Test of the Conserved Vector Current Hypothesis by beta-ray Angular Distribution Measurement in the Mass-8 System

TL;DR

This study tests the conserved vector current hypothesis by measuring beta-ray angular distributions in the mass-8 system, confirming some predictions but finding inconsistencies in second-forbidden terms.

Contribution

It provides experimental measurements of beta-ray angular correlations in 8Li and 8B, testing the CVC hypothesis and identifying discrepancies in second-forbidden terms.

Findings

Weak magnetism term matches CVC prediction

Second-forbidden term shows inconsistency with CVC

Results support partial validation of CVC hypothesis

Abstract

The beta-ray angular correlations for the spin alignments of 8Li and 8B have been observed in order to test the conserved vector current (CVC) hypothesis. The alignment correlation terms were combined with the known beta-alpha-angular correlation terms to determine all the matrix elements contributing to the correlation terms. The weak magnetism term, 7.5\pm0.2, deduced from the beta-ray correlation terms was consistent with the CVC prediction 7.3\pm0.2, deduced from the analog-gamma-decay measurement based on the CVC hypothesis. However, there was no consistent CVC prediction for the second-forbidden term associated with the weak vector current. The experimental value for the second-forbidden term was 1.0 \pm 0.3, while the CVC prediction was 0.1 \pm 0.4 or 2.1 \pm 0.5.