Time-reversal asymmetries in * *Supported in part by the National Key Research and Development Program of China (2020YFC2201501) and the National Natural Science Foundation of China (NSFC) (12147103)

Abstract

We study the decays of with . We examine the full angular distributions with polarized , where the T-odd observables are identified. We discuss the possible effects of new physics (NP) and find that the T-odd observables are sensitive to them as they vanish in the standard model. Special attention is given to the interference of (pseudo)scalar operators with (axial)vector operators in polarized , which are studied for the first time. Their effects are proportional to the lepton masses and therefore may evade the constraint from at the LHCb naturally. As is uncontaminated by the charmonia resonance, it provides a clean background to probe NP. In addition, we show that the experimental central value of in at the LHCb can be explained by the NP case, which couples to the right-handed quarks and leptons. The polarization fraction of at the LHCb is found to be consistent with zero regardless of the NP scenarios.