Rare FCNC radiative leptonic Bs,d → γ l+l decays in the SM

Dmitri Melikhov (Corresponding author), Anastasiia Kozachuk, Nikolai Nikitin

Publications: Contribution to journalMeeting abstract/Conference paperPeer Reviewed


We report our recent results [1] for long-distance QCD effects in the flavour-changing neutral current radiative leptonic decays B → γ ℓ+, ℓ = {e, µ }. One encounters here two distinct types of long-distance effects: those encoded in the B → γ transition form factors induced by the b → q quark currents, and those related to the charm-loop effects. We calculate the B → γ form factors in a broad range of the momentum transfers making use of the relativistic dispersion approach based on the constituent quark picture which has proven to provide reliable predictions for many weak-transition form factors. Concerning the description of the charm-loop contributions, we point out two observations: First, the precise description of the charmonium resonances, in particular, the relative phases between ψ and ψ , has impact on the differential distributions and on the forward-backward asymmetry, AFB, in a broad range of q2 ≥ 5 GeV2. Second, the shape of AFB in B → γ ℓ+ and in B → V ℓ+ (V the vector meson) in the q2-region between ψ and ψ provides an unambiguous probe of the relative phases between ψ and ψ . Fixing the latter will lead to a sizeable reduction of the theoretical uncertainties in AFB at q2 = 5 − 9 GeV2 where it has the sensitivity to physics beyond the SM.

Original languageEnglish
Article number274
Number of pages8
JournalProceedings of Science (PoS)
Publication statusPublished - 2019
Event13th Quark Confinement and the Hadron Spectrum, Confinement 2018 - Maynooth, Ireland
Duration: 31 Jul 20186 Aug 2018

Austrian Fields of Science 2012

  • 103034 Particle physics

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