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Test of Time Reversal Invariance in Stopped Kaon Decay
The transverse muon polarization (PT) in K+ decay is an excellent CP- or T- violating observable to study since any non-zero value > 10-5 would imply new physics beyond the minimal standard model. Furthermore, since PT involves phases between both the quark-quark and lepton-lepton couplings it probes a different region of parameter space than the neutron dipole moment or K0 decay experiments. We have measured the T-violating triple product correlation between the m+ spin and the p0 and m+ momenta in stopped K+ decays at the 12 GeV PS at the National Laboratory for High Energy Physics in Tsukuba, Japan. An analysis of our complete data set (11.8 million good K+ decays) indicates no evidence for any T-violation (PT < 0.0051 at the 90 % confidence level). The details of our experiment and the various systematic errors will be presented along with our new constraints on extensions to the standard model.