Observation of B^0_(s) -> J/\psi f_1(1285) decays and measurement of the f_1(1285) mixing angle

R. Aaij , Y. Amhis (1) , S. Barsuk (1) , O. Callot (1) , J. He (1) , O. Kochebina (1) , J. Lefrançois (1) , F. Machefert (1) , A. Martin Sanchez (1) , M. Nicol (1) , P. Robbe (1) , M.-H. Schune (1) , M. Teklishyn (1) , A. Vallier (1) , B. Viaud (1) , E. Ben-Haim (2) , M. Benayoun (2) , P. David (2) , L. del Buono (2) , A. Martens (2) , D.A. Milanes (2) , F. Polci (2) , Ziad Zj Ajaltouni (3) , M. Baalouch (3) , E. Cogneras (3) , O. Deschamps (3) , I. El Rifai (3) , M. Grabalosa Gándara (3) , Pierre Henrard (3) , M. Hoballah (3) , R. Lefèvre (3) , L. Li Gioi (3) , J. Maratas (3) , S. Monteil (3) , V. Niess (3) , Pascal Perret (3) , Diego Alejandro Roa Romero (3) , C. Adrover (4) , E. Aslanides (4) , J. Cogan (4) , W. Kanso (4) , R. Legac (4) , O. Leroy (4) , G. Mancinelli (4) , E. Maurice (4) , A. Mordà (4) , M. Perrin-Terrin (4) , M. Sapunov (4) , J. Serrano (4) , A. Tsaregorodtsev (4) , I. de Bonis (5) , D. Decamp (5) , N. Déléage (5) , Ph. Ghez (5) , J.-P. Lees (5) , I.V. Machikhiliyan (5) , M.-N. Minard (5) , B. Pietrzyk (5) , W. Qian (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

Decays of Bs and B0 mesons into J/\psi \pi +\pi -\pi +\pi - final states, produced in pp collisions at the LHC, are investigated using data corresponding to an integrated luminosity of 3/fb collected with the LHCb detector. B^0_(s) -> J\psi f_1(1285) decays are seen for the first time, and the branching fractions are measured. Using these rates, the f_1(1285) mixing angle between strange and non-strange components of its wave function in the q-qbar structure model is determined to be \pm (24.0^{+3.1+0.6}_{-2.6-0.8}) degrees. Implications on the possible tetraquark nature of the f_1(1285) are discussed.

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

R. Aaij, Y. Amhis, S. Barsuk, O. Callot, J. He, et al.. Observation of B^0_(s) -> J/\psi f_1(1285) decays and measurement of the f_1(1285) mixing angle. Physical Review Letters, 2014, 112, pp.091802. ⟨10.1103/PhysRevLett.112.091802⟩. ⟨in2p3-00871239⟩