Updated measurements of exclusive $J/ψ$ and $ψ(2S)$ production cross-sections in $pp$ collisions at $\sqrt{s}=7$ TeV

Abstract

The differential cross-section as a function of rapidity has been measured for the exclusive production of $J/ψ$ and $ψ(2S)$ mesons in proton-proton collisions at $\sqrt{s}=7$ TeV, using data collected by the LHCb experiment, corresponding to an integrated luminosity of 930 pb$^{-1}$. The cross-sections times branching fractions to two muons having pseudorapidities between 2.0 and 4.5 are measured to be $$\begin{array}{rl} σ_{pp\rightarrow J/ψ\rightarrow{μ^+}{μ^-}}(2.0<η_{μ^\pm }<4.5)=&291\pm 7\pm19 {\rm \ pb},\\ σ_{pp\rightarrowψ(2S)\rightarrow{μ^+}{μ^-}}(2.0<η_{μ^\pm}<4.5)=&6.5\pm 0.9\pm 0.4 {\rm \ pb},\end{array}$$ where the first uncertainty is statistical and the second is systematic. The measurements agree with next-to-leading order QCD predictions as well as with models that include saturation effects.

17 pages, 7 figures