Measurements of the ?(1S), ?(2S), and ?(3S) differential cross sections in pp collisions at s=7TeV

Abstract

Differential cross sections as a function of transverse momentum pT are presented for the production of ?(nS) (n = 1, 2, 3) states decaying into a pair of muons. Data corresponding to an integrated luminosity of 4.9fb?1 in pp collisions at s=7TeV were collected with the CMS detector at the LHC. The analysis selects events with dimuon rapidity |y| >1.2 and dimuon transverse momentum in the range 10 >pT >100GeV. The measurements show a transition from an exponential to a power-law behavior at pT?20GeV for the three ? states. Above that transition, the ?(3S) spectrum is significantly harder than that of the ?(1S). The ratios of the ?(3S) and ?(2S) differential cross sections to the ?(1S) cross section show a rise as pT increases at low pT, then become flatter at higher pT