Prospects of discovering new physics in rare charm decays

Abstract

The LHCb bounds on the branching ratio of the rare decay (Formula presented.) and the constraints on the branching ratio of (Formula presented.) in the nonresonant regions enable us to improve constraints on new physics contributions. Using the effective Lagrangian approach we determine the sizes of the Wilson coefficients allowed by the existing LHCb bounds on rare charm decays. Then we discuss contributions to rare charm meson decay observables in several models of new physics: a model with an additional spin-1 weak triplet, leptoquark models, Two Higgs doublets model of type III, and a (Formula presented.) model. Here we complement the discussion by (Formula presented.) – (Formula presented.) oscillations data. Among the considered models, only leptoquarks can significantly modify the Wilson coefficients. Assuming that the differential decay width for (Formula presented.) receives a NP contribution, while the differential decay width for (Formula presented.) is Standard Model-like, we find that lepton flavor universality can be violated and might be observed at high dilepton invariant mass.