CMS collaboration (2257 authors)Calpas, BettyNayak, ArunaBargassa, PedrameBeirão Da Cruz E Silva, CristóvãoDi Francesco, AgostinoFaccioli, PietroFerreira Parracho, Pedro GuilhermeGallinaro, MicheleHollar, JonathanLeonardo, NunoLloret Iglesias, LaraRodrigues Antunes, JoaoSeixas, JoaoToldaiev, OleksiiVadruccio, DanieleVarela, JoaoVischia, PietroDavid Tinoco Mendes, AndreSilva, PedroMusella, PasqualePela, Joao2019-02-042019-02-042017-02-10http://dx.doi.org/10.1016/j.physletb.2016.12.009http://hdl.handle.net/10400.26/27124Measurements of two- and multi-particle angular correlations in pp collisions at s=5,7, and 13TeV are presented as a function of charged-particle multiplicity. The data, corresponding to integrated luminosities of 1.0pb−1 (5 TeV), 6.2pb−1 (7 TeV), and 0.7pb−1 (13 TeV), were collected using the CMS detector at the LHC. The second-order ( v2 ) and third-order ( v3 ) azimuthal anisotropy harmonics of unidentified charged particles, as well as v2 of KS0 and Λ/Λ‾ particles, are extracted from long-range two-particle correlations as functions of particle multiplicity and transverse momentum. For high-multiplicity pp events, a mass ordering is observed for the v2 values of charged hadrons (mostly pions), KS0 , and Λ/Λ‾ , with lighter particle species exhibiting a stronger azimuthal anisotropy signal below pT≈2GeV/c . For 13 TeV data, the v2 signals are also extracted from four- and six-particle correlations for the first time in pp collisions, with comparable magnitude to those from two-particle correlations. These observations are similar to those seen in pPb and PbPb collisions, and support the interpretation of a collective origin for the observed long-range correlations in high-multiplicity pp collisions.engjournal article2019-02-04