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

Abstract

Differential cross sections as a function of transverse momentum p[subscript 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[superscript −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<p[subscript T]<100 GeV. The measurements show a transition from an exponential to a power-law behavior at p[subscript T]≈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 p[subscript T] increases at low p[subscript T], then become flatter at higher p[subscript T].