gamma and psi leptonic decays as probes of solutions to the R (D (()*())) puzzle

Daniel Aloni, Aielet Efrati, Yuval Grossman, Yosef Nir

Research output: Contribution to journalArticlepeer-review


Experimental measurements of the ratios R(D-(*())) equivalent to Gamma(B -> D-(*())tau upsilon)/Gamma(B -> D-(*())l upsilon) (l=rho, mu) show a 3.9 sigma deviation from the Standard Model prediction. In the absence of light right-handed neutrinos, a new physics contribution to b -> c tau nu decays necessarily modifies also b (b) over tilde ->tau(+)tau(-) and/or c (c) over tilde tau(+)tau(-) transitions. These contributions lead to violation of lepton flavor universality in, respectively, gamma and psi leptonic decays. We analyze the constraints resulting from measurements of the leptonic vector-meson decays on solutions to the R(D-(*())) puzzle. Available data from BaBar and Belle can already disfavor some of the new physics explanations of this anomaly. Further discrimination can be made by measuring gamma (1S, 2S, 3S)->tau tau in the upcoming Belle II experiment.
Original languageEnglish
Article number19
Number of pages27
JournalJournal of High Energy Physics
Issue number6
StatePublished - 5 Jun 2017


  • Beyond Standard Model
  • Heavy Quark Physics
  • Precision QED

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


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