Measurement of T-violating transverse muon polarization in K+→π0 μν decay at J-PARC

At J-PARC, we propose the search for time reversal invariance violation by measuring the transverse muon polarization (PT) in the K+ -> pi(0) mu(+)v decays with stopped K+ beam. The physics potential in terms of discovery of new physics along with the power to constrain the exotic models is shown to be competitive with other experiments being planned or prepared. The detector system is an upgraded version of the KEK-PS E246 experiment. Major changes in the hardware are 1) highly segmented K+ target, 2) improved charged particle tracking by incorporating the state-of-art GEM detectors, 3) new readout system of the CsI(T1) calorimeter with APD, 4) introducing active polarimeters for muons and decay positrons, and 5) introducing a muon field magnet. These arrangements will reduce both statistical and systematic errors and attain Delta P-T similar to 10(-4).