Measurements of the Υ(1S), Υ(2S), and Υ(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 Υ(nS)(n=1,2,3) states decaying into a pair of muons. Data corresponding to an integrated luminosity of 4.9fb-1in pp collisions at vs=7 TeV 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<100 GeV. The measurements show a transition from an exponential to a power-law behavior at pT˜20 GeV for the three ? states. Above that transition, the ?(3S) spectrum is significantly harder than that of the ?(1S). The ratios of the Υ(3S)and Υ(2S) differential cross sections to the Υ(1S cross section show a rise as pT increases at low pT, then become flatter at higher pT.