Rapidity and transverse momentum dependence of inclusive J/psi production in pp collisions at $\sqrt{s} = 7~$TeV

Submission Date: 
02/05/2011
Article Information
Submission Form
System: 
p-p
Energy: 
7 TeV
Abstract Plain Text: 

The ALICE experiment at √ LHC has studied inclusive J/ψ production at central and forward the rapidities in pp collisions at s = 7 TeV. In this Letter, we report on the first results obtained detecting the J/ψ through its dilepton decay into e+ e− and μ + μ − pairs in the rapidity range |y| < 0.9 and 2.5 < y < 4, respectively, and with acceptance down to zero pT . In the dielectron channel the analysis was carried out on a data sample corresponding to an integrated luminosity Lint = 3.9 nb−1 and the number of signal events is NJ/ψ = 249 ± 27 (stat.) ± 20 (syst.); the corresponding figures in the dimuon channel are Lint = 15.6 nb−1 and NJ/ψ = 1924 ± 77 (stat.) ± 144 (syst.). The measured production cross sections are σJ/ψ (|y| < 0.9) = 10.7 ± 1.2 (stat.) ± 1.7 (syst.) +1.6 -2.3 (syst.pol.) ab and σJ/ψ (2.5 < y < 4) = 6.31 ± 0.25 (stat.) ± 0.80 (syst.) +0.95 −1.96 (syst.pol.) ab. The differential cross sections, in transverse momentum and rapidity, of the J/ψ were also measured.

 

Erratum: October 9th, 2012

We have identified a bias in the calculation of the cross section of J/ψ pro-
duction measured in the e+e− channel at central rapidity (|y| < 0.9) [1]. The
fraction of signal in the me+e− invariant mass range 2.92−3.16 GeV/c2 was
determined using a Monte Carlo simulation, based on PYTHIA [2,3], which
did not include the radiative decays of J/ψ (J/ψ !e+e−γ).