Observation of the $Λ_b^0\rightarrow J/ψp π^-$ decay

Journal article

The first observation of the Cabibbo-suppressed decay $\Lambda_b^0\rightarrow J/\psi p \pi^-$ is reported using a data sample of proton-proton collisions at 7 and 8 TeV, corresponding to an integrated luminosity of 3 $\rm fb^{-1}$. A prominent signal is observed and the branching fraction relative to the decay mode $\Lambda_b^0\rightarrow J/\psi p K^-$ is determined to be $$ \frac{{\cal B}(\Lambda_b^0\rightarrow J/\psi p \pi^-)}{{\cal B}(\Lambda_b^0\rightarrow J/\psi p K^-)}=0.0824\pm0.0025\:(\text{stat})\pm0.0042\:(\text{syst}). $$ A search for direct CP violation is performed. The difference in the CP asymmetries between these two decays is found to be $$ {\cal A}_{CP}(\Lambda_b^0\rightarrow J/\psi p \pi^-)-{\cal A}_{CP}(\Lambda_b^0\rightarrow J/\psi p K^-)=(+5.7\pm 2.4\:(\text{stat})\pm1.2\:(\text{syst}))\%, $$ which is compatible with CP symmetry at the $2.2\sigma$ level.

Authors: collaboration, L; Aaij, R; Adeva, B; Adinolfi, M; Affolder, A

• Publication status: Published
• Journal: Journal of High Energy Physics
• Volume: 07
• Issue: 7
• Pages: 103
• Publication date: 2014-06-03
• DOI: 10.1007/JHEP07(2014)103
• EISSN: 1029-8479
• ISSN: 1029-8479
• Keywords: hep-ex