Anomalous tqγ coupling effects in exclusive radiative B-meson decays

  • Xin-Qiang Li
  • Ya-Dong Yang
  • Xing-Bo Yuan


The top-quark FCNC processes will be searched for at the CERN LHC, which are correlated with the B-meson decays. In this paper, we study the effects of top-quark anomalous interactions tqγ in the exclusive radiative B → K γ and B → ργ decays. With the current experimental data of the branching ratios, the direct CP and the isospin asymmetries, bounds on the coupling κγ tcR from B → K γ and κγ tcR from B → ργ decays are derived, respectively. The bound on |κγ tcR | from \( \mathcal{B}\left( {B \to {K^*}\gamma } \right) \) is generally compatible with that from \( \mathcal{B}\left( {B \to {K_s}\gamma } \right) \). However, the isospin asymmetry ∆(K γ) further restrict the phase of κγ tcR , and the combined bound results in the upper limit, \( \mathcal{B}\left( {t \to c\gamma } \right) \)< 0.21%, which is lower than the CDF result. For real κγ tcR , the upper bound on \( \mathcal{B}\left( {t \to c\gamma } \right) \) is about of the same order as the 5σ discovery potential of ATLAS with an integrated luminosity of10 fb−1. For B → ργ decays, the NP contribution is enhanced by a large CKM factor |V ud /V td |, and the constraint on tuγ coupling is rather restrictive, \( \mathcal{B}\left( {t \to u\gamma } \right) \)< 1.44× 10−5. With refined measurements to be available at the LHCb and the future super-B factories, we can get close correlations between B →  and the rare t →  decays, which will be studied directly at the LHC ATLAS and CMS.


Beyond Standard Model B-Physics 


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Copyright information

© SISSA, Trieste, Italy 2011

Authors and Affiliations

  1. 1.Department of PhysicsHenan Normal UniversityXinxiangP.R. China
  2. 2.IFICUniversitat de València-CSICValènciaSpain
  3. 3.Institute of Particle PhysicsHuazhong Normal UniversityWuhanP.R. China
  4. 4.Key Laboratory of Quark & Lepton Physics, Ministry of EducationHuazhong Normal UniversityWuhanP.R. China

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