Further search for T-violation in the decay K^+ --> pi^0 mu^+ nu

TL;DR

This paper reports a new measurement of the transverse mu^+ polarization in K^+ decay, finding results consistent with no T-violation, thereby constraining possible new physics beyond the Standard Model.

Contribution

The study provides the most recent and combined measurement of mu^+ polarization in K^+ decay, improving limits on T-violation effects in this process.

Findings

Measured P_T = (-1.12 +- 2.17(stat) +- 0.90(syst))x10^{-3}

Found Im(ξ) = (-0.28 +- 0.69(stat) +- 0.30(syst))x10^{-2}

Results are consistent with no T-violation

Abstract

A new result for the transverse mu^+ polarization, P_T, in the decay K^+ --> pi^0 mu^+ nu has been obtained in the KEK E246 experiment. Combined with our earlier result, P_T = (-1.12 +- 2.17(stat) +- 0.90(syst))x10^{-3} and Im(\xi) = (-0.28 +- 0.69(stat) +- 0.30(syst))x10^{-2}, which are consistent with no T-violation.