J/psi Production as a Function of Charged Particle Multiplicity in pp Collisions at sqrt{s} = 7 TeV

B. Abelev , N. Arbor (1) , G. Conesa Balbastre (1) , J. Faivre (1) , C. Furget (1) , R. Guernane (1) , S. Kox (1) , Y. Mao (1) , J.S. Real (1) , R. Vernet (2) , I. Belikov (3) , B. Hippolyte (3) , S. Jangal (3) , C. Kuhn (3) , A. Maire (3) , C. Roy (3) , X. Sanchez Castro (3) , S. Senyukov (3) , R. Wan (3) , Laurent Aphecetche (4) , Guillaume Batigne (4) , M. Bregant (4) , H. Delagrange (4) , O. Driga (4) , Magali Estienne (4) , Marie Germain (4) , A. Lardeux (4) , F. Lefèvre (4) , M. Lenhardt (4) , L. Luquin (4) , Gines Martinez Garcia (4) , A. Mas (4) , L. Massacrier (4, 5) , A. Matyja (4) , Philippe Pillot (4) , Y. Schutz (4) , Alexandre Shabetai (4) , Diego Stocco (4) , C. Cheshkov (6) , B. Cheynis (5) , L. Ducroux (5) , Maxime Guilbaud (5) , J.-Y. Grossiord (6) , R. Tieulent (5) , A. Uras (5) , Y. Zoccarato (5) , A. Baldisseri (7) , H. Borel (7) , J. Castillo Castellanos (7) , J.L. Charvet (7) , C. Geuna (7) , S. Pal (7) , A. Rakoizafindrabe (7) , Sang Un Ahn (8) , Y.W. Baek (8) , A. Baldit (8) , V. Barret (8) , N. Bastid (8) , P. Crochet (8) , P. Dupieux (8) , R. Ichou (8) , X. Lopez (8) , F. Manso (8) , M. Marchisone (8) , S. Porteboeuf-Houssais (8) , P. Rosnet (8) , B. Vulpescu (8) , X. Zhang (8)

1 LPSC - Laboratoire de Physique Subatomique et de Cosmologie
2 CC-IN2P3 - Centre de Calcul de l'IN2P3
3 DRS-IPHC - Département Recherches Subatomiques
4 SUBATECH - Laboratoire SUBATECH Nantes
5 IPNL - Institut de Physique Nucléaire de Lyon
6 ALICE
7 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
8 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand

The ALICE collaboration reports the measurement of the inclusive J/psi yield as a function of charged particle pseudorapidity density dN_{ch}/deta in pp collisions at sqrt{s} = 7 TeV at the LHC. J/psi particles are detected for p_t > 0, in the rapidity interval |y| < 0.9 via decay into e+e-, and in the interval 2.5 < y < 4.0 via decay into mu+mu- pairs. An approximately linear increase of the J/psi yields normalized to their event average (dN_{J/psi}/dy)/ with (dN_{ch}/deta)/ is observed in both rapidity ranges, where dN_{ch}/deta is measured within |eta| < 1 and p_t > 0. In the highest multiplicity interval with = 24.1, corresponding to four times the minimum bias multiplicity density, an enhancement relative to the minimum bias J/psi yield by a factor of about 5 at 2.5 < y < 4 (8 at |y| < 0.9) is observed.

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

B. Abelev, N. Arbor, G. Conesa Balbastre, J. Faivre, C. Furget, et al.. J/psi Production as a Function of Charged Particle Multiplicity in pp Collisions at sqrt{s} = 7 TeV. Physics Letters B, 2012, 712, pp.165-175. ⟨10.1016/j.physletb.2012.04.052⟩. ⟨in2p3-00669824⟩