Evidence for collectivity in pp collisions at the LHC
Measurements 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 (7TeV), 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. Finally, 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.
- Research Organization:
- Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Argonne National Laboratory (ANL), Argonne, IL (United States); Univ. of Kansas, Lawrence, KS (United States). Center for Research
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- Contributing Organization:
- CMS Collaboration
- Grant/Contract Number:
- AC02-07CH11359; FG02-96ER40981
- OSTI ID:
- 1335706
- Alternate ID(s):
- OSTI ID: 1294440; OSTI ID: 2325013
- Report Number(s):
- FERMILAB-PUB-16-255-CMS; CMS-HIN-16-010; CERN-EP-2016-147; arXiv:1606.06198; S037026931630747X; PII: S037026931630747X
- Journal Information:
- Physics Letters B, Journal Name: Physics Letters B Vol. 765 Journal Issue: C; ISSN 0370-2693
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- Netherlands
- Language:
- English
Web of Science
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