Isolation of Flow and Nonflow Correlations by Two- and Four-Particle Cumulant Measurements of Azimuthal Harmonics in $\sqrt{s_{_{\rm NN}}} =$ 200 GeV Au+Au Collisions

• Main Authors: Aggarwal, M. M, Bellwied, R, Bunzarov, I, Caines, H, Campbell, J. M, Cebra, D, Chaloupka, P, Chattopadhyay, S, Chen, L, Chikanian, A, Contin, G, Leyva, A. Davila, de Souza, R. Derradi, di Ruzza, B, Djawotho, P, Du, C. M, Dunkelberger, L. E, Dunlop, J. C, Eun, L, Fatemi, R, Filip, P, Gangadharan, D. R, Girard, M, Gliske, S, Grosnick, D, Gunarathne, D. S, Gupta, S, Guryn, W, Harris, J. W, Huang, H. Z, Humanic, T. J, Igo, G, Judd, E. G, Kisel, I, Kisiel, A, Konzer, J, Kosarzewski, L. K, Kravtsov, P, Kulakov, I, Kumar, L, Kycia, R. A, Landry, K. D, Lauret, J, Li, C, Ljubicic, T, Luo, X, Ma, G. L, Majka, R, Matis, H. S, Minaev, N. G, Mondal, M. M, Mustafa, M. K, Nandi, B. K, Nayak, T. K, Odyniec, G, Ogawa, A, Oh, K, Oldag, E. W, Panebratsev, Y, Porter, J, Poskanzer, A. M, Ramachandran, S, Raniwala, S, Rogachevskiy, O. V, Rusnakova, O, Sahu, P. K, Salur, S, Schmidke, W. B, Seyboth, P, Shanmuganathan, P. V, Sharma, B, Shen, W. Q, Sichtermann, E. P, Skoby, M. J, Sorensen, P, Srivastava, B, Stevens, J. R, Sun, X, Sun, Y, Surrow, B, Svirida, D. N, Tang, Z, Tarnowsky, T, Vandenbroucke, M, Vasiliev, A. N, Vertesi, R, Vokal, S, Wada, M, Wang, H, Webb, G, Wieman, H, Xu, Y, Yang, Y, Ye, Z, Yi, L, Zhang, J. B, Zhang, J. L, Zhong, C, Zhu, X, Zyzak, M
• Format: Journal Article
• Language: English
• Published: 06.09.2014
• Subjects: Physics - Nuclear Experiment
• DOI: 10.48550/arxiv.1409.2043

Phys. Lett. B 745 (2015) 40 A data-driven method was applied to measurements of Au+Au collisions at $\sqrt{s_{_{\rm NN}}} =$ 200 GeV made with the STAR detector at RHIC to isolate pseudorapidity distance $\Delta\eta$-dependent and $\Delta\eta$-independent correlations by using two- and four-particle azimuthal cumulant measurements. We identified a component of the correlation that is $\Delta\eta$-independent, which is likely dominated by anisotropic flow and flow fluctuations. It was also found to be independent of $\eta$ within the measured range of pseudorapidity $|\eta|<1$. The relative flow fluctuation was found to be $34\% \pm 2\% (stat.) \pm 3\% (sys.)$ for particles of transverse momentum $p_{T}$ less than $2$ GeV/$c$. The $\Delta\eta$-dependent part may be attributed to nonflow correlations, and is found to be $5\% \pm 2\% (sys.)$ relative to the flow of the measured second harmonic cumulant at $|\Delta\eta| > 0.7$.