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Journal of High Energy Physics

, 2017:184 | Cite as

B s 0  → +γ as a test of lepton flavor universality

  • Diego Guadagnoli
  • Méril Reboud
  • Roman Zwicky
Open Access
Regular Article - Theoretical Physics

Abstract

We discuss a number of strategies to reduce the ℬ(B s 0  → +γ) theoretical error, and make such a measurement a new probe of the interactions that are interesting in the light of present-day flavor discrepancies. In particular, for low di-lepton invariant mass we propose to exploit the close parenthood between ℬ(B s 0  → +γ) and the measured ℬ(B s 0  → ϕ(→K+K)γ). For high q2, conversely, we exploit the fact that the decay is dominated by two form-factor combinations, plus contributions from broad charmonium that we model accordingly. We construct the ratio Rγ , akin to RK and likewise sensitive to lepton-universality violation. Provided the two rates in this ratio are integrated in a suitable region that minimises bremsstrahlung contributions while maximising statistics, the ratio is very close to unity and the form-factor dependence cancels to an extent that makes it a new valuable probe of lepton-universality violating contributions in the effective Hamiltonian. We finally speculate on additional ideas to extract short-distance information from resonance regions, which are theoretically interesting but statistically limited at present.

Keywords

Heavy Quark Physics Beyond Standard Model Effective Field Theories 

Notes

Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

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Copyright information

© The Author(s) 2017

Authors and Affiliations

  • Diego Guadagnoli
    • 1
  • Méril Reboud
    • 1
    • 2
  • Roman Zwicky
    • 3
    • 4
  1. 1.Laboratoire d’Annecy-le-Vieux de Physique Théorique UMR5108Université de Savoie Mont-Blanc et CNRSAnnecy-le-Vieux CedexFrance
  2. 2.École Normale Supérieure de LyonLyon Cedex 07France
  3. 3.School of Physics and AstronomyUniversity of EdinburghEdinburghU.K.
  4. 4.Department of PhysicsUniversity of ZürichZürichSwitzerland

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