Investigation on effects of new physics in transitions *

Abstract

Abstract Anomalies in decays induced by ( ) transitions may imply lepton flavor universality violations, which raises questions on such phenomena in the D decays induced by transitions. Current measurements of the pure leptonic and semi-leptonic D decays agree with the standard model (SM) predictions, and such agreements can be used to constrain the new physics (NP) contributions. In this work, we extend SM by assuming general effective Hamiltonians describing the transitions including the full set of the four-fermion operators. With the latest experimental data, we perform a least fit of the Wilson coefficient corresponding to each operator. The results indicate that the Wilson coefficients of tensor and scalar operators in the muon sector are in the order of while others are in the order of . The lepton flavor universality could be violated by interactions with the scalar operators. We also determine that the pure leptonic decays are significantly sensitive to scalar operators. The effects of NP on the semi-leptonic decays with electron final state are negligible; however, for the decays with the muon final state, the effects of scalar and tensor operators will appear in the forward-backward asymmetries and the muon helicity asymmetries of decays. The future measurements of these decays in the BESIII and Belle II experiments will facilitate the evaluation of NP effects.