Cluster properties from two-particle angular correlations in p+p collisions at ps = 0.9 and 2.36 TeV at CMS

Two-particle angular correlations have been measured by the CMS detector in proton-proton collisions at center of mass energies of 0.9, 2.36 and 7 TeV over a broad range of pseudorapidity (h) and azimuthal angle (f). At all three energies, a complex two-dimensional correlation structure in Dh and Df is observed. In the context of an independent cluster model of short-range correlations, the cluster size and its decay width are extracted from the two-particle pseudorapidity correlation function and compared with previous measurements in proton-proton and proton-antiproton collisions, as well as PYTHIA predictions. The results at 0.9 TeV are in agreement with previous measurements. The new results at 2.36 and 7 TeV represent the highest-energy measurements at a particle collider to date.