First measurement of the T-violating muon polarization in the decay K^+ --> mu^+ nu gamma

We present the result of the first measurement of the T-violating muon polarization P_T in the decay K^+ --> mu^+ nu gamma. This polarization is sensitive to new sources of CP-violation in the Higgs sector. Using data accumulated in the period 1996-98 we have obtained P_T = (-0.64 +- 1.85(stat) +- 0.10(syst))x10^{-2} which is consistent with no T-violation in this decay.Comment: 11 pages, 8 figure

Improved measurement of the K+->pi+nu(nu)over-bar branching ratio

An additional event near the upper kinematic limit for K+-->pi(+)nu(nu) over bar has been observed by experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+-->pi(+)nu(nu) over bar)=(1.47(-0.89)(+1.30))x10(-10) based on three events observed in the pion momentum region 211<P<229 MeV/c. At the measured central value of the branching ratio, the additional event had a signal-to-background ratio of 0.9

CsI(Tl) calorimeter with photodiode readout to search for T-violation in K-mu 3 decay

A new electromagnetic calorimeter is designed for the experiment E246 at KEK, It consists of 768 CsI(Tl) crystals with PIN-diode readout. A short description of the calorimeter design and performance is given

Test of time reversal invariance in K-mu 3 decay

An experiment E246 at the 12-GeV proton synchrotron at KEK (KEK-PS), which is searching for the T-violating transverse muon polarization (P-mu(perpendicular to)) in K+ --> pi (0)mu (+)nu decay, is described. The search is sensitive to new mechanisms of T or CP violation beyond the Standard Model. The initial results of P-mu(perpendicular to) = -0.0042+/-0.0049(stat.)+/-0.0009(syst.) and the T-violating parameter Im(xi) = -0.013+/- 0.016(stat.) +/- 0.003(syst.) were determined from the data taken in 1996 and 1997