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

Differential cross sections as a function of transverse momentum p T 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 4.9 fb − 1 in pp collisions at √s=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 Υ states. Above that transition, the Υ(3S) spectrum is significantly harder than that of the Υ(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.