Limits on right-handed charged weak currents from a polarization-asymmetry correlation experiment with 107In.

Abstract

A new technique, based on relative measurements of the longitudinal polarization (P) of positrons emitted in two opoosite directions with respect to the nuclear polarization (R=${\mathit{P}}^{\mathrm{\ensuremath{-}}}$/${\mathit{P}}^{+}$), is used to provide constraints on extensions of the standard model (${\mathit{R}}_{0}$). The first result, i.e., R/${\mathit{R}}_{0}$=0.926\ifmmode\pm\else\textpm\fi{}0.041, was obtained with $^{107}\mathrm{In}$. Interpreted in the framework of left-right symmetric models and assuming no mixing, it provides a 90% C.L. lower limit of 225 GeV/${\mathit{c}}^{2}$ for the mass of a possible right-handed charged W gauge boson, reducing the mass range allowed by other semileptonic experiments.