Left-Right Symmetry in Nuclear Beta Decay under Investigation with a New Bhabha Polarimeter

Abstract

Precise observation of the ratio $\frac{P_{\mathrm{F}}}{P_{\mathrm{GT}}}$ of beta polarizations for Fermi and Gamow-Teller decays can provide stringent constraints on electroweak models. The result of a first measurement, with a Bhabha polarimeter of novel design, is $\frac{P_{\mathrm{F}}}{P_{\mathrm{GT}}}=0.986\mathrm{}\pm 0.038$. Resulting bounds, being comparable to those from existing muon polarization experiments, are limited by statistics. Precision of order ${10}^{-3\mathrm{}}$ or better may be anticipated with an extended system.