LHC Seminar

# Long-Range Near-Side Angular Correlations in Proton-Proton Interactions in CMS.

## by Guido Tonelli (Universita' di Pisa, INFN, CERN) , Gunther Roland (Massachusetts Institute of Technology (MIT))

Europe/Zurich
500-1-001 - Main Auditorium (CERN)

### 500-1-001 - Main Auditorium

#### CERN

400
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Description
The CMS Collaboration 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 7TeV over a broad range of pseudorapidity (η) and azimuthal angle (φ) are presented using data collected with the CMS detector at the LHC. Short-range correlations in ∆η, which are studied in minimum bias events, are characterized using a simple independent cluster parameterization in order to quantify their strength (cluster size) and their extent in η (cluster decay width). Long-range azimuthal correlations are studied more differentially as a function of charged particle multiplicity and particle transverse momentum using a 980nb−1 data set at 7TeV. In high multiplicity events, a pronounced structure emerges in the two-dimensional correlation function for particles in intermediate pT’s of 1-3GeV/c, 2.0< |∆η|<4.8 and ∆φ≈0. This is the ﬁrst observation of such a ridge-like feature in two-particle correlation functions in pp or p-pbar collisions.