  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 inverse nanobarns. The correlations are studied over a
broad range of pseudorapidity (abs(eta) < 2.4) and over the full azimuth (phi)
as a function of charged particle multiplicity and transverse momentum (pt). In
high-multiplicity events, a long-range (abs(Delta eta) > 2.0), near-side (Delta
phi approximately 0) structure emerges in the two-particle Delta eta-Delta phi
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 sqrt(s) = 7 TeV. The present
measurement extends the study of near-side long-range correlations up to
charged particle multiplicities of N[ch] approximately 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.
