Measurement of long-range near-side two-particle angular correlations in pp collisions at $\sqrt s =$13 TeV

Abstract

Results on two-particle angular correlations for charged particles produced in pp collisions at a center-of-mass energy of 13 TeV are presented. The data were taken with the CMS detector at the LHC and correspond to an integrated luminosity of about 270 nb-1. The correlations are studied over a broad range of pseudorapidity (|η|<2.4) and over the full azimuth (φ) as a function of charged particle multiplicity and transverse momentum (pT). In high-multiplicity events, a long-range (|Δη|>2.0), near-side (Δφ≈0) structure emerges in the two-particle Δη-Δφ correlation functions. The magnitude of the correlation exhibits a pronounced maximum in the range 1.0<pT<2.0 GeV/c and an approximately linear increase with the charged particle multiplicity, with an overall correlation strength similar to that found in earlier pp data at s=7 TeV. The present measurement extends the study of near-side long-range correlations up to charged particle multiplicities Nch∼180, a region so far unexplored in pp collisions. The observed long-range correlations are compared to those seen in pp, pPb, and PbPb collisions at lower collision energies.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Department of Science and Technology, Republic of South AfricaFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Bundesministerium für Wissenschaft, Forschung und WirtschaftMinistry of Education of the People's Republic of ChinaNational Science and Technology Development AgencyDepartment of Atomic Energy, Government of IndiaGeneral Secretariat for Research and Technology