Measurement of long-range multiparticle azimuthal correlations with the subevent cumulant method in <i>pp</i> and <i>p</i> plus Pb collisions with the ATLAS detector at the CERN Large Hadron Collider



Aaboud, M, Aad, G, Abbott, B, Abdinov, O, Abeloos, B, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H
et al (show 2886 more authors) (2018) Measurement of long-range multiparticle azimuthal correlations with the subevent cumulant method in <i>pp</i> and <i>p</i> plus Pb collisions with the ATLAS detector at the CERN Large Hadron Collider. PHYSICAL REVIEW C, 97 (2). pp. 472-475.

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Abstract

A detailed study of multi-particle azimuthal correlations is presented using $pp$ data at $\sqrt{s}=5.02$ and 13 TeV, and $p$+Pb data at $\sqrt{s_{\rm{NN}}}=5.02$ TeV, recorded with the ATLAS detector at the LHC. The azimuthal correlations are probed using four-particle cumulants $c_{n}\{4\}$ and flow coefficients $v_n\{4\}=(-c_{n}\{4\})^{1/4}$ for $n=2$ and 3, with the goal of extracting long-range multi-particle azimuthal correlation signals and suppressing the short-range correlations. The values of $c_{n}\{4\}$ are obtained as a function of the average number of charged particles per event, $\left\langle N_{\rm{ch}} \right\rangle$, using the recently proposed two-subevent and three-subevent cumulant methods, and compared with results obtained with the standard cumulant method. The three-subevent method is found to be least sensitive to short-range correlations, which originate mostly from jets with a positive contribution to $c_{n}\{4\}$. The three-subevent method gives a negative $c_{2}\{4\}$, and therefore a well-defined $v_2\{4\}$, nearly independent of $\left\langle N_{\rm{ch}} \right\rangle$, which provides direct evidence that the long-range multi-particle azimuthal correlations persist to events with low multiplicity. Furthermore, $v_2\{4\}$ is found to be smaller than the $v_2\{2\}$ measured using the two-particle correlation method, as expected for long-range collective behavior. Finally, the measured values of $v_2\{4\}$ and $v_2\{2\}$ are used to estimate the number of sources relevant for the initial eccentricity in the collision geometry.

Item Type: Article
Additional Information: 20 pages plus author list + cover pages (37 pages total), 13 figures, submitted to Phys. Rev. C., All figures including auxiliary figures can be found at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2017-02/
Uncontrolled Keywords: Hadron-Hadron Collision, Multi-Particle Correlation
Depositing User: Symplectic Admin
Date Deposited: 10 Apr 2018 09:29
Last Modified: 17 Oct 2023 21:26
DOI: 10.1103/PhysRevC.97.024904
Open Access URL: https://doi.org/10.1103/PhysRevC.97.024904
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3019639