Observation of the $\Lambda_b^0\rightarrow J/\psi p \pi^-$ decay - IN2P3 - Institut national de physique nucléaire et de physique des particules Access content directly
Journal Articles Journal of High Energy Physics Year : 2014

Observation of the $\Lambda_b^0\rightarrow J/\psi p \pi^-$ decay

R. Aaij
  • Function : Author
J. Cogan
O. Leroy
J. Serrano


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 $$ {\cal A}_{CP}(\Lambda_b^0\rightarrow J/\psi p \pi^-)-{\cal A}_{CP}(\Lambda_b^0\rightarrow J/\psi p K^-)=(+5.7\pm 2.3\:(\text{stat})\pm1.2\:(\text{syst}))\%, $$ which is compatible with CP symmetry at the $2.2\sigma$ level.

Dates and versions

in2p3-00999792 , version 1 (04-06-2014)



R. Aaij, Y. Amhis, S. Barsuk, M. Borsato, O. Callot, et al.. Observation of the $\Lambda_b^0\rightarrow J/\psi p \pi^-$ decay. Journal of High Energy Physics, 2014, 7, pp.103. ⟨10.1007/JHEP07(2014)103⟩. ⟨in2p3-00999792⟩
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