A new limit on time-reversal violation in beta decay: Results of the emiTII experiment.

We have measured the triple correlation D<Jn> · (pe × pv) with a polarized cold-neutron beam at the NIST Center for Neutron Research by observing proton-electron coincidences in the decay of polarized neutrons. A non-zero value of D can arise due to parity-even-time-reversal-odd interactions that imply CP violation due to the CPT theorem. Final-state effects also contribute to D at the level of 10-5 and can be calculated with precision of 1% or better. The D coefficient is sensitive to the phase, of λ the ratio of axial-vector and vector amplitudes as well as to scalar and tensor interactions that could arise due to beyond-Standard-Model physics such as leptoquarks. Over 300 million proton-electron coincidence events were used in a blind analysis with the result D = [-0.96±1.89(stat)±1.01(sys)]×10-4. [ABSTRACT FROM AUTHOR]