D → ρℓ + ℓ − decays in the QCD factorization approach

Abstract

We consider rare semileptonic decays of a heavy D-meson into a light vector meson in the framework of QCD factorization. In contrast to the corresponding B-meson decays, the naive factorization hypothesis does not even serve as a first approximation. Rather, the decay amplitudes appear to be dominated by non-factorizable dynamics, e.g. through annihilation topologies, which are particularly sensitive to long-distance hadronic contributions. We therefore pay particular attention to intermediate vector-meson resonances appearing in quark-loop and annihilation topologies. Compared to the analogous B-meson decays, we identify a number of effects that result in very large theoretical uncertainties for differential decay rates. Some of these effects are found to cancel in the ratio of partially integrated decay rates for transversely and longitudinally polarized ρ mesons. On the phenomenological side this implies a very limited potential to constrain physics beyond the Standard Model by means of these decays.

The new physics reach of null tests with $$D \rightarrow \pi \ell \ell $$ and $$D_s \rightarrow K \ell \ell $$ decays

“…Null test observables, already key to ongoing and future precision programs in rare semileptonic b-decays [8,9], are indispensable when methods to achieve sufficient theoretical control on decay amplitudes are not available. This is exactly the case in charm decays, subject to notorious resonance pollution and poor convergence of the heavy quark expansion [10]. Null tests are based on approximate symmetry limits, which follow from parametric or structural features of the Standard Model (SM) that do not have to be present in general models beyond the SM.…”

Λc→N form factors from lattice QCD and phenomenology of Λc→Meinel1 2018Phys. Rev. D645592View full textAdd to dashboardCite

“…Recent theoretical studies of mesonic rare charm decays such as D þ → π þ μ þ μ − can be found in Refs. [9][10][11]. This work focuses on the decay Λ c → pμ þ μ − , which was recently analyzed by the LHCb Collaboration [12].…”

Two loop virtual corrections to $$b\rightarrow (d,s)\ell ^+\ell ^-$$ b → ( d , s )

“…Exemplary, non-factorizable corrections to form factors are commonly considered as one unreducible uncertainty while interpreting beyond the standard model (BSM) physics. Furthermore, in c → u + − transitions, non-factorizable corrections yield the largest perturbative contribution due to the Glashow-Iliopolus-Maiani (GIM) cancellation of factorizable contributions [2][3][4]. In this paper, we improve on the current state by calculating the two loop virtual corrections to any heavy to light transition, including c and b decays, induced by current-current operators for arbitrary invariant dilepton mass q 2 .…”

“…We emphasize that available results for b → (d, s) transitions only cover different limits, i.e. zero masses, small and large q 2 ranges, and that results for c → u transitions have become available only recently [4,12]. The analytic calculation presented in this paper covers the full q 2 range, arbitrary masses and electric charges.…”