Evidence for collectivity in pp collisions at the LHC

• Main Authors: Abercrombie, Daniel Robert (Contributor), Allen, Brandon Leigh (Contributor), Apyan, Aram (Contributor), Barbieri, Richard Alexander (Contributor), Baty, Austin Alan (Contributor), Bi, Ran (Contributor), Bierwagen, Katharina (Contributor), Brandt, Stephanie Akemi (Contributor), Cali, Ivan Amos (Contributor), Busza, Wit (Contributor), Demiragli, Zeynep (Contributor), Di Matteo, Leonardo (Contributor), Gomez-Ceballos, Guillelmo (Contributor), Goncharov, Maxim (Contributor), Hsu, Dylan George (Contributor), Iiyama, Yutaro (Contributor), Innocenti, Gian Michele (Contributor), Klute, Markus (Contributor), Kovalskyi, Dmytro (Contributor), Krajczar, Krisztian F. (Contributor), Lai, Yue Shi (Contributor), Lee, Yen-Jie (Contributor), Levin, Andrew D. (Contributor), Luckey Jr, P David (Contributor), Marini, Andrea Carlo (Contributor), McGinn, Christopher Francis (Contributor), Mironov, Camelia Maria (Contributor), Narayanan, Siddharth Madhavan (Contributor), Niu, Xinmei (Contributor), Paus, Christoph M. E. (Contributor), Roland, Christof E (Contributor), Roland, Gunther M (Contributor), Salfeld-Nebgen, Jakob Maxillian Henry (Contributor), Stephans, George S. F. (Contributor), Sumorok, Konstanty C (Contributor), Tatar, Kaya (Contributor), Varma, Mukund Madhav (Contributor), Velicanu, Dragos Alexandru (Contributor), Veverka, Jan (Contributor), Wang, J. (Contributor), Wyslouch, Boleslaw (Contributor), Yang, Mingming (Contributor), Wyslouch, Victoria (Contributor), Wang, Ta-Wei (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: Elsevier BV, 2018-06-27T14:11:09Z.
• Subjects: Article
• Online Access: Get fulltext

 Measurements of two- and multi-particle angular correlations in pp collisions at √s=5, 7, and 13 TeV are presented as a function of charged-particle multiplicity. The data, corresponding to integrated luminosities of 1.0pb[superscript −1] (5 TeV), 6.2pb[superscript −1] (7 TeV), and 0.7pb[superscript −1] (13 TeV), were collected using the CMS detector at the LHC. The second-order (v[subscript 2]) and third-order (v[subscript 3]) azimuthal anisotropy harmonics of unidentified charged particles, as well as v[subscript 2] of K[superscript 0][subscript s] and Λ/[bar over 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 v[subscript 2] values of charged hadrons (mostly pions), K[superscript 0][subscript s], and Λ/[bar overΛ], with lighter particle species exhibiting a stronger azimuthal anisotropy signal below p[subscript T] ≈2 GeV/c. For 13 TeV data, the v[subscript 2] 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. Keywords: CMS, Physics, Heavy ion, Ridge, Correlation, pp