First Measurement of the Underlying Event Activity at the LHC with \sqrt{s} = 0.9 TeV.
Journal Article

Published: Saturday, November 06, 2010
Citation: European Physical Journal C - Particles and Fields, Volume 70, Pages 555-572 1006.2083

Authors (1 total): J. Rohlf


A measurement of the underlying activity in scattering processes with p T scale in the GeV region is performed in proton–proton collisions at s=09  TeV, using data collected by the CMS experiment at the LHC. Charged particle production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged particles with pseudorapidity |η|<2, p T >0.5 GeV/c, and azimuthal direction transverse to that of the leading object.