Observation of double charm production involving open charm in pp collisions at $\sqrt{s}$=7 TeV

R. Aaij , I. de Bonis (1) , D. Decamp (1) , Ph. Ghez (1) , P. Hopchev (1) , J.-P. Lees (1) , I.V. Machikhiliyan (1) , M.-N. Minard (1) , B. Pietrzyk (1) , S. t'Jampens (1) , V. Tisserand (1) , E. Tournefier (1) , S. Barsuk (2) , O. Callot (2) , J. He (2) , B. Jean-Marie (2) , J. Lefrançois (2) , F. Machefert (2) , A. Martin Sanchez (2) , M. Nicol (2) , P. Robbe (2) , M.-H. Schune (2) , B. Viaud (2) , I. Videau (2) , Ziad Zj Ajaltouni (3) , O. Deschamps (3) , Pierre Henrard (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) , B. Khanji (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)

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

The production of $J/\psi$ mesons accompanied by open charm, and of pairs of open charm hadrons are observed in pp collisions at a centre-of-mass energy of 7 TeV using an integrated luminosity of $355pb^{-1}$ collected with the LHCb detector. Model independent measurements of absolute cross-sections are given together with ratios to the measured $J/\psi$ and open charm cross-sections. The properties of these events are studied and compared to theoretical predictions.

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

R. Aaij, I. de Bonis, D. Decamp, Ph. Ghez, P. Hopchev, et al.. Observation of double charm production involving open charm in pp collisions at $\sqrt{s}$=7 TeV. Journal of High Energy Physics, 2012, 6, pp.141. ⟨10.1007/JHEP06(2012)141⟩. ⟨in2p3-00697167⟩