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

ATLAS Collaboration

doi:10.1103/PhysRevC.97.024904

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

ATLAS Collaboration

European Organization for Nuclear Research
Université Mohamed Premier and LPTPM
CPPM
University of Oklahoma
Institute of Physics Azerbaijan National Academy of Sciences
CNRS Centre National de la Recerche Scientifique
University Health Network, Toronto
Santa Cruz Institute for Particle Physics
University of Sussex
Tel Aviv University
Technion Israel Institute of Technology
University of Oregon
Stockholm University
The Oskar Klein Centre
INFN
Sezione di Trieste
THE ABDUS SALAM INTERNATIONAL CENTRE FOR THEORETICAL PHYSICS
Department of Clinical Physics
King's College London
The University of Tokyo
AGH University of Science and Technology
Northern Illinois University
Pettenkofer School of Public Health
STFC Rutherford Appleton Laboratory
University of Belgrade
Alexandru Ioan Cuza University of Iasi
Laboratorio de Instrumentacao e Fisica Experimental de Particulas
University of Granada
Universidade Nova de Lisboa
Boston University
Joint Institute for Nuclear Research, Dubna
INFN Sezione di Roma Tor Vergata
Policlinico Universitario Tor Vergata Clinica Dermatologica
university of kyoto
Department of Clinical Sciences
Global Health Institute
Academy of Sciences
INFN Sezione di Bologna
Alma Mater Studiorum Universita di Bologna
University of Victoria
INFN National Institute for Nuclear Physics
National Scientific and Technical Research Council Argentina (CONICET)
Karakter Child and Adolescent Psychiatry University Centre
Horia Hulubei National Institute of Physics and Nuclear Engineering
National Technical University of Athens
Czech Technical University in Prague
INFN Sezione di Lecce
University of Salento
INFN Sezione di Milano
University of Chicago
Columbia University
Birmingham Business School

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Abstract

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.

Original language	English
Article number	024904
Journal	PHYSICAL REVIEW C
Volume	97
Issue number	2
DOIs	https://doi.org/10.1103/PhysRevC.97.024904
Publication status	Published - 12 Feb 2018

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@article{4a909693e3cc4571bff1a530f440574b,

title = "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",

abstract = "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.",

author = "M. Aaboud and G. Aad and B. Abbott and O. Abdinov and B. Abeloos and Abidi, \{S. H.\} and Abouzeid, \{O. S.\} and Abraham, \{N. L.\} and H. Abramowicz and H. Abreu and R. Abreu and Y. Abulaiti and Acharya, \{B. S.\} and S. Adachi and L. Adamczyk and J. Adelman and M. Adersberger and T. Adye and Affolder, \{A. A.\} and Y. Afik and T. Agatonovic-Jovin and C. Agheorghiesei and Aguilar-Saavedra, \{J. A.\} and Ahlen, \{S. P.\} and F. Ahmadov and G. Aielli and S. Akatsuka and H. Akerstedt and {\AA}kesson, \{T. P.A.\} and E. Akilli and Akimov, \{A. V.\} and Alberghi, \{G. L.\} and J. Albert and P. Albicocco and \{Alconada Verzini\}, \{M. J.\} and Alderweireldt, \{S. C.\} and M. Aleksa and Aleksandrov, \{I. N.\} and C. Alexa and G. Alexander and T. Alexopoulos and M. Alhroob and B. Ali and M. Aliev and G. Alimonti and J. Alison and Alkire, \{S. P.\} and Allbrooke, \{B. M.M.\} and Allen, \{B. W.\} and Allport, \{P. P.\} and \{ATLAS Collaboration\}",

year = "2018",

month = feb,

day = "12",

doi = "10.1103/PhysRevC.97.024904",

language = "English",

volume = "97",

journal = "PHYSICAL REVIEW C",

issn = "2469-9985",

publisher = "American Physical Society",

number = "2",

}

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 - 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 - Allen, B. W.

AU - Allport, P. P.

AU - ATLAS Collaboration

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 - https://www.scopus.com/pages/publications/85042222202

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 -

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

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