Measurement of ψ(2S) meson production in pp collisions at $\sqrt{s}=7\ \mbox{TeV}$

Abstract

The differential cross-section for the inclusive production of <i>ψ</i>(2<i>S</i>) mesons in <i>pp</i> collisions at [Formula: see text] has been measured with the LHCb detector. The data sample corresponds to an integrated luminosity of 36 pb^-1. The <i>ψ</i>(2<i>S</i>) mesons are reconstructed in the decay channels <i>ψ</i>(2<i>S</i>)→<i>μ</i>⁺<i>μ</i>^- and <i>ψ</i>(2<i>S</i>)→<i>J</i>/<i>ψπ</i>⁺<i>π</i>^-, with the <i>J</i>/<i>ψ</i> meson decaying into two muons. Results are presented both for promptly produced <i>ψ</i>(2<i>S</i>) mesons and for those originating from <i>b</i>-hadron decays. In the kinematic range <i>p</i>_T(<i>ψ</i>(2<i>S</i>))≤16 GeV/<i>c</i> and 2<<i>y</i>(<i>ψ</i>(2<i>S</i>))≤4.5 we measure [Formula: see text] where the last uncertainty on the prompt cross-section is due to the unknown <i>ψ</i>(2<i>S</i>) polarization. Recent QCD calculations are found to be in good agreement with our measurements. Combining the present result with the LHCb <i>J</i>/<i>ψ</i> measurements we determine the inclusive branching fraction [Formula: see text] where the last uncertainty is due to the [Formula: see text], [Formula: see text] and [Formula: see text] branching fraction uncertainties.