Measurement of the X(3872) production cross section via decays to J/ψπ+π− in pp collisions at √s = 7 TeV

Abstract

The production of the X(3872) is studied in pp collisions at √ s = 7 TeV, using decays to J/ψπ+π −, where the J/ψ decays to two muons. The data were recorded by the CMS experiment and correspond to an integrated luminosity of 4.8 fb−1 . The measurements are performed in a kinematic range in which the X(3872) candidates have a transverse momentum 10 < pT < 50 GeV and rapidity |y| < 1.2. The ratio of the X(3872) and ψ(2S) cross sections times their branching fractions into J/ψπ+π − is measured as a function of pT. In addition, the fraction of X(3872) originating from B decays is determined. From these measurements the prompt X(3872) differential cross section times branching fraction as a function of pT is extracted. The π +π − mass spectrum of the J/ψπ+π − system in the X(3872) decays is also investigated.