Branching Fraction of the Decay $B^{+}\to {\pi }^{+}{\tau }^{+}{\tau }^{-}$ and Lepton Flavor Universality Test via the Ratio $R_{\pi }(\tau /\mu )$

Ahmed Ali, Alexander Ya. Parkhomenko, Irina M. Parnova

Among (semi)leptonic rare $B$-decays induced by the $b\to d$ flavor changing neutral current, the decay $B^{+}\to {\pi }^{+}{\mu }^{+}{\mu }^{-}$ is the only one observed so far experimentally. Relat…