Looking for new physics via semi-leptonic and leptonic rare decays of D and D _s

Abstract

It is well recognized that looking for new physics at lower energy colliders is a tendency which is complementary to high energy machines such as LHC. Based on large database of BESIII, we may have a unique opportunity to do a good job. In this paper we calculate the branching ratios of semi-leptonic processes D + s → K + e − e + , D + s → K + e − µ + and leptonic processes D 0 → e − e + , D 0 → e − µ + in the frames of U (1) ′ model, 2HDM and unparticle separately. It is found that both the U (1) ′ and 2HDM may influence the semi-leptonic decay rates, but only the U (1) ′ offers substantial contributions to the pure leptonic decays and the resultant branching ratio of D 0 → e − µ + can be as large as 10 −7 ∼ 10 −8 which might be observed at the future super τ -charm factory.

First Observation of D+→ημ+νμ and Measurement of Its Decay Dy

“…DOI: 10.1103/PhysRevLett.124.231801 In the standard model (SM), the couplings between three families of leptons and gauge bosons are independent of lepton flavors. This property is known as lepton flavor universality (LFU) [1][2][3][4]. Semileptonic (SL) decays of pseudoscalar mesons, which are well understood in the SM, offer an ideal platform to test LFU and search for new physics effects.…”

Charm decays

“…D → P and D → PP , SM CP-asymmetries are small, A SM CP ∼ Im λ b λ s ∼ 10 −3 . Further SM null test are given in terms of angular observables, [26,33,35,39,40,48,49,50,51,52,53,54,55,56,57,58,59].…”

“…CP asymmetry and forward-backward asymmetry within BSM models. Table is a compilation of the results given in[26,33,35,39,40,48,49,50,51,52,53,54,55,56,57,58,59]. …”

Constraints on 2ℓ2q operators from μ↔e flavor-changing meson decays

“…More model-independent studies, that take into account loop corrections (or equivalently, renormalization group running) have also been performed for µ ↔ e flavour change [46,47]. Finally, with respect to the calculations in this manuscript, the leptonic branching ratio of pseudoscalar mesons is well-known, and can be found in [26,28,48,49] and semi-leptonic branching ratios in various scenarios can be found in [50,51,52,53,54,55,56,57,58].…”