Evidence for the strangeness-changing weak decay $\hat{I}{ž}_b^{-}\to \hat{I}{›}_b^0\ddot{I}{€}^{-}$

Abstract

Using a $pp$ collision data sample corresponding to an integrated luminosity of 3.0~fb${}^{-1}$, collected by the LHCb detector, we present the first search for the strangeness-changing weak decay $\hat{I}{ž}_b^{-}\to \hat{I}{›}_b^0\ddot{I}{€}^{-}$. No $b$ hadron decay of this type has been seen before. A signal for this decay, corresponding to a significance of 3.2 standard deviations, is reported. The relative rate is measured to be $\frac{f_{\hat{I}{ž}_b^{-}}}{f_{\hat{I}{›}_b^0}}\mathcal{B}(\hat{I}{ž}_b^{-}\to \hat{I}{›}_b^0\ddot{I}{€}^{-})=(5.7\pm 1.8_{-0.9}^{+0.8})\times 10^{-4}$, where $f_{\hat{I}{ž}_b^{-}}$ and $f_{\hat{I}{›}_b^0}$ are the $b\to \hat{I}{ž}_b^{-}$ and $b\to \hat{I}{›}_b^0$ fragmentation fractions, and $\mathcal{B}(\hat{I}{ž}_b^{-}\to \hat{I}{›}_b^0\ddot{I}{€}^{-})$ is the branching fraction. Assuming $f_{\hat{I}{ž}_b^{-}}/f_{\hat{I}{›}_b^0}$ is bounded between 0.1 and 0.3, the branching fraction $\mathcal{B}(\hat{I}{ž}_b^{-}\to \hat{I}{›}_b^0\ddot{I}{€}^{-})$ would lie in the range from $(0.57\pm 0.21)\%$ to $(0.19\pm 0.07)\%$.

7 pages, 2 figures, All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-047.html