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

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 ($|\eta|<2.4$) and over the full azimuth ($\phi$) as a function of charged particle multiplicity and transverse momentum ($p_{\mathrm{T}}$). In high-multiplicity events, a long-range ($|\Delta\eta|>2.0$), near-side ($\Delta\phi\approx 0$) structure emerges in the two-particle $\Delta\eta$-$\Delta\phi$ correlation functions. The observed correlations resemble the long-range correlations seen in high-multiplicity pp, pPb and PbPb collisions at lower collision energies. The magnitude of the correlation exhibits a pronounced maximum in the range $1.0 < p_{\mathrm{T}} < 2.0$ GeV and an approximately linear increase with the charged particle multiplicity. The overall correlation strength at $\sqrt{s}$ = 13 TeV is similar to that found in earlier pp data at $\sqrt{s}$ = 7 TeV, but is measured up to much higher multiplicity values.