TY - JOUR
T1 - Measurement of long-range multiparticle azimuthal correlations with the subevent cumulant method in pp and p +Pb collisions with the ATLAS detector at the CERN Large Hadron Collider
AU - ATLAS Collaboration
AU - Aaboud, M.
AU - Aad, G.
AU - Abbott, B.
AU - Abdinov, O.
AU - Abeloos, B.
AU - Abidi, S. H.
AU - Abouzeid, O. S.
AU - Abraham, N. L.
AU - Abramowicz, H.
AU - Abreu, H.
AU - Abreu, R.
AU - Abulaiti, Y.
AU - Acharya, B. S.
AU - Adachi, S.
AU - Adamczyk, L.
AU - Adelman, J.
AU - Adersberger, M.
AU - Adye, T.
AU - Affolder, A. A.
AU - Afik, Y.
AU - Agatonovic-Jovin, T.
AU - Agheorghiesei, C.
AU - Aguilar-Saavedra, J. A.
AU - Ahlen, S. P.
AU - Ahmadov, F.
AU - Aielli, G.
AU - Akatsuka, S.
AU - Akerstedt, H.
AU - Åkesson, T. P.A.
AU - Akilli, E.
AU - Akimov, A. V.
AU - Alberghi, G. L.
AU - Albert, J.
AU - Albicocco, P.
AU - Alconada Verzini, M. J.
AU - Alderweireldt, S. C.
AU - Aleksa, M.
AU - Aleksandrov, I. N.
AU - Alexa, C.
AU - Alexander, G.
AU - Alexopoulos, T.
AU - Alhroob, M.
AU - Ali, B.
AU - Aliev, M.
AU - Alimonti, G.
AU - Alison, J.
AU - Alkire, S. P.
AU - Allbrooke, B. M.M.
AU - Connell, S. H.
AU - Govender, N.
N1 - Publisher Copyright:
©2018 CERN, for the ATLAS Collaboration. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP.
PY - 2018/2/12
Y1 - 2018/2/12
N2 - A detailed study of multiparticle azimuthal correlations is presented using pp data at s=5.02 and 13 TeV, and p+Pb data at sNN=5.02 TeV, recorded with the ATLAS detector at the CERN Large Hadron Collider. The azimuthal correlations are probed using four-particle cumulants cn{4} and flow coefficients vn{4}=(-cn{4})1/4 for n=2 and 3, with the goal of extracting long-range multiparticle azimuthal correlation signals and suppressing the short-range correlations. The values of cn{4} are obtained as a function of the average number of charged particles per event, Nch, using the recently proposed two-subevent and three-subevent cumulant methods, and compared with results obtained with the standard cumulant method. The standard method is found to be strongly biased by short-range correlations, which originate mostly from jets with a positive contribution to cn{4}. The three-subevent method, on the other hand, is found to be least sensitive to short-range correlations. The three-subevent method gives a negative c2{4}, and therefore a well-defined v2{4}, nearly independent of Nch, which implies that the long-range multiparticle azimuthal correlations persist to events with low multiplicity. Furthermore, v2{4} is found to be smaller than the v2{2} measured using the two-particle correlation method, as expected for long-range collective behavior. Finally, the measured values of v2{4} and v2{2} are used to estimate the number of sources relevant for the initial eccentricity in the collision geometry. The results based on the subevent cumulant technique provide direct evidence, in small collision systems, for a long-range collectivity involving many particles distributed across a broad rapidity interval.
AB - A detailed study of multiparticle azimuthal correlations is presented using pp data at s=5.02 and 13 TeV, and p+Pb data at sNN=5.02 TeV, recorded with the ATLAS detector at the CERN Large Hadron Collider. The azimuthal correlations are probed using four-particle cumulants cn{4} and flow coefficients vn{4}=(-cn{4})1/4 for n=2 and 3, with the goal of extracting long-range multiparticle azimuthal correlation signals and suppressing the short-range correlations. The values of cn{4} are obtained as a function of the average number of charged particles per event, Nch, using the recently proposed two-subevent and three-subevent cumulant methods, and compared with results obtained with the standard cumulant method. The standard method is found to be strongly biased by short-range correlations, which originate mostly from jets with a positive contribution to cn{4}. The three-subevent method, on the other hand, is found to be least sensitive to short-range correlations. The three-subevent method gives a negative c2{4}, and therefore a well-defined v2{4}, nearly independent of Nch, which implies that the long-range multiparticle azimuthal correlations persist to events with low multiplicity. Furthermore, v2{4} is found to be smaller than the v2{2} measured using the two-particle correlation method, as expected for long-range collective behavior. Finally, the measured values of v2{4} and v2{2} are used to estimate the number of sources relevant for the initial eccentricity in the collision geometry. The results based on the subevent cumulant technique provide direct evidence, in small collision systems, for a long-range collectivity involving many particles distributed across a broad rapidity interval.
UR - http://www.scopus.com/inward/record.url?scp=85042222202&partnerID=8YFLogxK
U2 - 10.1103/PhysRevC.97.024904
DO - 10.1103/PhysRevC.97.024904
M3 - Article
AN - SCOPUS:85042222202
SN - 2469-9985
VL - 97
JO - Physical Review C
JF - Physical Review C
IS - 2
M1 - 024904
ER -