# Y and ψ leptonic decays as probes of solutions to the R(D (*)) puzzle

Journal of High Energy Physics, Jun 2017

Experimental measurements of the ratios $$R\left({D}^{\left(\ast \right)}\right)\equiv \frac{\Gamma \left(B\to {D}^{\left(*\right)}\tau v\right)}{\Gamma \left(B\to {D}^{\left(*\right)}\ell v\right)}\left(\ell =e,\mu \right)$$ show a 3.9σ deviation from the Standard Model prediction. In the absence of light right-handed neutrinos, a new physics contribution to b → cτν decays necessarily modifies also $$b\overline{b}\to {\tau}^{+}{\tau}^{-}$$ and/or $$c\overline{c}\to {\tau}^{+}{\tau}^{-}$$ transitions. These contributions lead to violation of lepton flavor universality in, respectively, Y and ψ 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 Y(1S, 2S, 3S) → ττ in the upcoming Belle II experiment.

This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1007%2FJHEP06%282017%29019.pdf

Daniel Aloni, Aielet Efrati, Yuval Grossman, Yosef Nir. Y and ψ leptonic decays as probes of solutions to the R(D (*)) puzzle, Journal of High Energy Physics, 2017, 1-27, DOI: 10.1007/JHEP06(2017)019