J/psi production from proton-proton collisions at sqrt(s) = 200 GeV

Abstract

J/psi production has been measured in proton-proton collisions at sqrt(s)= 200 GeV over a wide rapidity and transverse momentum range by the PHENIX experiment at RHIC. Distributions of the rapidity and transverse momentum, along with measurements of the mean transverse momentum and total production cross section are presented and compared to available theoretical calculations. The total J/psi cross section is 3.99 +/- 0.61(stat) +/- 0.58(sys) +/- 0.40(abs) micro barns. The mean transverse momentum is 1.80 +/- 0.23(stat) +/- 0.16(sys) GeV/c.

Figures (4)

• Figure 1: The invariant mass spectra for dielectron and dimuon pairs. Unlike-sign pairs are shown as solid lines, the sum of like-sign pairs as dashed lines.
• Figure 2: The $J/\psi$$p_T$ distributions for the dielectron and dimuon measurements, with statistical uncertainties. The solid line is a phenomenological fit of the form $1/(2 \pi p_T)~d\sigma/dp_T~=~A~(1 + (p_T/B)^2)^{-6}$. The dashed line is an exponential fit. The CSM (dot-dashed) and COM (dotted) calculations are from rhic_nrqcd.
• Figure 3: The central rapidity point is from $J/\psi \rightarrow e^+e^-$, the others from $J/\psi \rightarrow \mu^+\mu^-$. The brackets represent systematic uncertainties. All curves have their overall normalization fitted to the data. The Pythia shape was used to determine the cross section. There is an overall 10% absolute normalization error not shown.
• Figure 4: (a) The present $J/\psi$ mean $p_T$ value compared with previous measurements at lower energy. The linear fit parameters are $p$ = 0.53, $q$ = 0.19. (b) The present $J/\psi$ total cross section compared with previous measurements at other values of $\sqrt{s}$. The curves are discussed in the text.