First observation of the decay $B^{+} \rightarrow \pi^{+} \mu^{+} \mu^{-}$

R. Aaij , S. Barsuk (1) , O. Callot (1) , J. He (1) , B. Jean-Marie (1) , J. Lefrançois (1) , F. Machefert (1) , A. Martin Sanchez (1) , M. Nicol (1) , P. Robbe (1) , M.-H. Schune (1) , B. Viaud (1) , I. Videau (1) , E. Ben-Haim (2) , M. Benayoun (2) , P. David (2) , L. del Buono (2) , A. Martens (2) , Ziad Zj Ajaltouni (3) , E. Cogneras (3) , O. Deschamps (3) , I. El Rifai (3) , Pierre Henrard (3) , M. Hoballah (3) , Marwa Jahjah-Hussein (3) , R. Lefèvre (3) , L. Li Gioi (3) , S. Monteil (3) , V. Niess (3) , Pascal Perret (3) , Diego Alejandro Roa Romero (3) , Krzysztof Grzegorz Sobczak (3) , C. Adrover (4) , E. Aslanides (4) , J. Cogan (4) , R. Legac (4) , O. Leroy (4) , G. Mancinelli (4) , E. Maurice (4) , M. Perrin-Terrin (4) , M. Sapunov (4) , J. Serrano (4) , A. Tsaregorodtsev (4) , I. de Bonis (5) , D. Decamp (5) , Ph. Ghez (5) , P. Hopchev (5) , J.-P. Lees (5) , I.V. Machikhiliyan (5) , M.-N. Minard (5) , B. Pietrzyk (5) , S. t'Jampens (5) , V. Tisserand (5) , E. Tournefier (5)

1 LAL - Laboratoire de l'Accélérateur Linéaire
2 LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
3 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand
4 CPPM - Centre de Physique des Particules de Marseille
5 LAPP - Laboratoire d'Annecy de Physique des Particules

A discovery of the rare decay $B^{+} \rightarrow \pi^{+} \mu^{+} \mu^{-}$ is presented. This decay is observed for the first time, with 5.2 $\sigma$ significance. The observation is made using $pp$ collision data, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected with the LHCb detector. The measured branching fraction is (2.3 $\pm$ 0.6 (stat.) $\pm$ 0.1 (syst.))$\times 10^{-8}$, and the ratio of the $B^{+} \rightarrow \pi^{+} \mu^{+} \mu^{-}$ and $B^{+} \rightarrow \K^{+} \mu^{+} \mu^{-}$ branching fractions is measured to be 0.053 $\pm$ 0.014 (stat.) $\pm$ 0.001 (syst.).

Domaines: Physique des Hautes Energies - Expérience [hep-ex]

R. Aaij, S. Barsuk, O. Callot, J. He, B. Jean-Marie, et al.. First observation of the decay $B^{+} \rightarrow \pi^{+} \mu^{+} \mu^{-}$. Journal of High Energy Physics, 2012, 12, pp.125. ⟨10.1007/JHEP12(2012)125⟩. ⟨in2p3-00741291⟩