Volume 273 - 16th International Conference on B-Physics at Frontier Machines (BEAUTY2016) - Semileptonic and rare decays
Semileptonic at B-factories (RD, RD*)
J. Hasenbusch
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Published on: 2016 November 15
Abstract
Recently, the measurements of R(D) and R(D*) at the B-factories showed a significant tension with the SM. Here, a new analysis of R(D*) using a semileptonically tagged sample by the Belle collaboration is presented. The new result of $R(D^*) = 0.302 \pm 0.030{\rm (stat)} \pm 0.011{\rm(sys)}$ is compatible with the previous measurements by Belle, BaBar and LHCb and increases the tension with the SM to $4\sigma$. A study of $B \to D^(*)\pi\pi\ell\nu$ by BaBar is shown which allows for better constraints on the semileptonic B-meson background in R(D) and R(D*) analyses. They find a value of $\mathcal{B}(B \to D^(*)\pi\pi\ell\nu) = 0.51^{+0.30}_{-0.15}\%$. Furthermore, BaBar studied the decay $B \to D^*\pi\pi\pi$ which is an important background, too, especially when it comes to analyses with hadronic $\tau$ final states. Their analysis yields $\mathcal{B}(B \to D^(*)\pi\pi\pi = (7.37 \pm 0.11 \pm 0.31 ) \cdot 10^{-3}$.
DOI: https://doi.org/10.22323/1.273.0047
Open Access