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J/ψ production as a function of charged particle multiplicity in pp collisions at √s = 7 TeV

The ALICE Collaboration reports the measurement of the relative J/ψ yield as a function of charged particle pseudorapidity density dNch/dη in pp collisions at √s = 7 TeV at the LHC. J/ψ particles are detected for pt > 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 μ+μ− pairs. An approximately linear increase of the J/ψ yields normalized to their event average (dNJ/ψ /dy)/dNJ/ψ /dy with (dNch/dη)/dNch/dη is observed in both rapidity ranges, where dNch/dη is measured within |η| < 1 and pt > 0. In the highest multiplicity interval with dNch/dη(bin) = 24.1, corresponding to four times the minimum bias multiplicity density, an enhancement relative to the minimum bias J/ψ yield by a factor of about 5 at 2.5 < y < 4 (8 at |y| < 0.9) is observed.

ALICE; LHC; CERN; strange particle; pp; 7 TeV; J/Psi; Production

The ALICE Collaboration