Observation of Long-Range Near-Side Angular Correlations in Proton-Proton Collisions at the LHC
Journal Article

Published: Monday, September 27, 2010
Citation: Journal of High Energy Physics, Volume 1009, Pages 091
arXiv.org: 1009.4122
Link: http://www.springerlink.com/content/18j075w18321q5h6/

Authors (1 total): J. Rohlf

Abstract:

Results on two-particle angular correlations for charged particles emitted in proton-proton collisions at center-of-mass energies of 0.9, 2.36, and 7 TeV are presented, using data collected with the CMS detector over a broad range of pseudorapidity (η) and azimuthal angle (ϕ). Short-range correlations in Δη, which are studied in minimum bias events, are characterized using a simple “independent cluster” parametrization in order to quantify their strength (cluster size) and their extent in η (cluster decay width). Long-range azimuthal correlations are studied differentially as a function of charged particle multiplicity and particle transverse momentum using a 980 nb−1 data set at 7 TeV. In high multiplicity events, a pronounced structure emerges in the two-dimensional correlation function for particle pairs with intermediate p T of 1–3 GeV/c, 2.0 < |Δη| < 4.8 and Δϕ ≈ 0. This is the first observation of such a long-range, near-side feature in two-particle correlation functions in pp or pp collisions.