Evidence for the strangeness-changing weak decay ${\Xi }_b^{-}\to {\Lambda }_b^0{\pi }^{-}$

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 ${\Xi }_b^{-}\to {\Lambda }_b^0{\pi }^{-}$. 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 $\frac{f_{{\Xi }_b^{-}}}{f_{{\Lambda }_b^0}}\mathcal{B}({\Xi }_b^{-}\to {\Lambda }_b^0{\pi }^{-})=(5.7\pm 1.8_{-0.9}^{+0.8})\times 10^{-4}$, where $f_{{\Xi }_b^{-}}$ and $f_{{\Lambda }_b^0}$ are the $b\to {\Xi }_b^{-}$ and $b\to {\Lambda }_b^0$ fragmentation fractions, and $\mathcal{B}({\Xi }_b^{-}\to {\Lambda }_b^0{\pi }^{-})$ is the branching fraction. Assuming $f_{{\Xi }_b^{-}}/f_{{\Lambda }_b^0}$ is bounded between 0.1 and 0.3, the branching fraction $\mathcal{B}({\Xi }_b^{-}\to {\Lambda }_b^0{\pi }^{-})$ 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

References in corpus (7)

• Big-Bang Nucleosynthesis
• Measurements of prompt charm production cross-sections in $pp$ collisions at $\sqrt{s}=13\mathrm{TeV}$
• Precision measurement of the mass and lifetime of the ${\Xi }_b^0$ baryon
• Precision measurement of the mass and lifetime of the Xi_b^- baryon
• Light-Quark Decays in Heavy Hadrons
• Measurement of the ${\Xi }_b^{-}$ and ${\Omega }_b^{-}$ baryon lifetimes
• The decays ${\Xi }_b\to {\Lambda }_b\pi$ and diquark correlations in hyperons

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