Observation of long-range, near-side angular correlations in proton-proton collisions at the LHC
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 pT 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 \( p\overline p \) collisions.
- CMS collaboration, The CMS Experiment at the CERN LHC, 2008 JINST 3 S08004. Google Scholar
- CMS collaboration, Measurement of Tracking Efficiency, CMS PAS TRK-10-002 (2010).
- Proceedings of 1st workshop of Multiple Parton Interactions at the LHC, Perugia, Italy, October 27–31, 2008 [DESY-PROC-2009-06].Google Scholar
Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.