Onset of Constituent Quark Number Scaling in Heavy-Ion Collisions at RHIC

STAR Collaboration

doi:10.1103/2qhx-cp79

Onset of Constituent Quark Number Scaling in Heavy-Ion Collisions at RHIC

STAR Collaboration

Texas A and M University
Czech Technical University in Prague
Univ of Mining and Metallurgy
Panjab University
VECC Kolkata
Kent State University
Brookhaven National Laboratory
Fudan University
Abilene Christian University
Universidad de Tarapacá
Shandong University
University of California, Riverside
Iiser Tirupati
University of Houston
University of Jammu
SUNY
Nuclear Physics Institute of the Cas
Ohio State University
Shanghai Institute of Applied Physics, Chinese Academy of Sciences
Yale University
University of California, Davis
Lawrence Berkeley National Laboratory
University of California at Los Angeles
Indiana University Bloomington
National Institute of Technology, Durgapur
Guangxi Normal University
Tsinghua University
University of California at Berkeley
Eotvos Lorand University (ELTE)
UIC ECE-CSN-Lab
Heidelberg University
Iiser Berhampur
Rice University
Tsukuba University
University of Kentucky
Universite della Calabria
Purdue University
Southern Connecticut State University
Institute of Modern Physics Chinese Academy of Sciences
Technische Universität Darmstadt
Temple University
Valparaiso University
Huzhou University
The American University in Cairo Cairo
University of Chinese Academy of Sciences
Academica Sinica
National Cheng Kung University
Central China Normal University
University of Science and Technology of China
Wayne State University
Warsaw Institute of Technology
Frankfurt Institute for Advanced Studies
Lehigh University
Wuhan University of Science and Technology
South China Normal University
Texas Southern University
University of Texas at Austin
National Institute of Science Education and Research
Sejong University
Rutgers University–New Brunswick
Max-Planck-Institut für Physik
Creighton University
Iit Patna
Ball State University
Michigan State University
Argonne National Laboratory
United States Naval Academy
Chongqing University
Second Hospital of Lanzhou University

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

Partonic collectivity is one of the necessary signatures for the formation of quark-gluon plasma in high-energy nuclear collisions. Number of constituent quarks (NCQ) scaling has been observed for hadron elliptic flow v2 in top energy nuclear collisions at the Relativistic Heavy Ion Collider and the LHC, and this has been theoretically suggested as strong evidence for partonic collectivity. In this Letter, a systematic analysis of v2 of π±, K±, KS0, p, and Λ in Au+Au collisions at sNN=3.2, 3.5, 3.9, and 4.5 GeV, with the STAR experiment at the Relativistic Heavy Ion Collider, is presented. NCQ scaling is markedly violated at 3.2 GeV, consistent with a hadronic-interaction dominated equation of state. However, as the collision energy increases, a gradual evolution to NCQ scaling is observed. This beam-energy dependence of v2 for all hadrons studied provides evidence for the onset of dominant partonic interactions by sNN=4.5 GeV.

Original language	English
Article number	072301
Journal	Physical Review Letters
Volume	135
Issue number	7
DOIs	https://doi.org/10.1103/2qhx-cp79
State	Published - 15 Aug 2025
Externally published	Yes

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10.1103/2qhx-cp79

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@article{47842755dc7a4e3eb02eb431dd2220ef,

title = "Onset of Constituent Quark Number Scaling in Heavy-Ion Collisions at RHIC",

abstract = "Partonic collectivity is one of the necessary signatures for the formation of quark-gluon plasma in high-energy nuclear collisions. Number of constituent quarks (NCQ) scaling has been observed for hadron elliptic flow v2 in top energy nuclear collisions at the Relativistic Heavy Ion Collider and the LHC, and this has been theoretically suggested as strong evidence for partonic collectivity. In this Letter, a systematic analysis of v2 of π±, K±, KS0, p, and Λ in Au+Au collisions at sNN=3.2, 3.5, 3.9, and 4.5 GeV, with the STAR experiment at the Relativistic Heavy Ion Collider, is presented. NCQ scaling is markedly violated at 3.2 GeV, consistent with a hadronic-interaction dominated equation of state. However, as the collision energy increases, a gradual evolution to NCQ scaling is observed. This beam-energy dependence of v2 for all hadrons studied provides evidence for the onset of dominant partonic interactions by sNN=4.5 GeV.",

author = "\{STAR Collaboration\} and Aboona, \{B. E.\} and J. Adam and L. Adamczyk and I. Aggarwal and Aggarwal, \{M. M.\} and Z. Ahammed and Alshammri, \{A. K.\} and Aschenauer, \{E. C.\} and S. Aslam and J. Atchison and V. Bairathi and X. Bao and K. Barish and S. Behera and R. Bellwied and P. Bhagat and A. Bhasin and S. Bhatta and Bhosale, \{S. R.\} and J. Bielcik and J. Bielcikova and Brandenburg, \{J. D.\} and C. Broodo and Cai, \{X. Z.\} and H. Caines and \{Calder{\'o}n De La Barca S{\'a}nchez\}, M. and D. Cebra and J. Ceska and I. Chakaberia and P. Chaloupka and Chan, \{B. K.\} and Z. Chang and A. Chatterjee and D. Chen and J. Chen and Chen, \{J. H.\} and Q. Chen and Z. Chen and J. Cheng and Y. Cheng and W. Christie and X. Chu and S. Corey and Crawford, \{H. J.\} and M. Csan{\'a}d and G. Dale-Gau and A. Das and Deppner, \{I. M.\} and A. Deshpande and A. Dhamija",

note = "Publisher Copyright: {\textcopyright} 2025 American Physical Society.",

year = "2025",

month = aug,

day = "15",

doi = "10.1103/2qhx-cp79",

language = "English",

volume = "135",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "7",

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TY - JOUR

T1 - Onset of Constituent Quark Number Scaling in Heavy-Ion Collisions at RHIC

AU - STAR Collaboration

AU - Aboona, B. E.

AU - Adam, J.

AU - Adamczyk, L.

AU - Aggarwal, I.

AU - Aggarwal, M. M.

AU - Ahammed, Z.

AU - Alshammri, A. K.

AU - Aschenauer, E. C.

AU - Aslam, S.

AU - Atchison, J.

AU - Bairathi, V.

AU - Bao, X.

AU - Barish, K.

AU - Behera, S.

AU - Bellwied, R.

AU - Bhagat, P.

AU - Bhasin, A.

AU - Bhatta, S.

AU - Bhosale, S. R.

AU - Bielcik, J.

AU - Bielcikova, J.

AU - Brandenburg, J. D.

AU - Broodo, C.

AU - Cai, X. Z.

AU - Caines, H.

AU - Calderón De La Barca Sánchez, M.

AU - Cebra, D.

AU - Ceska, J.

AU - Chakaberia, I.

AU - Chaloupka, P.

AU - Chan, B. K.

AU - Chang, Z.

AU - Chatterjee, A.

AU - Chen, D.

AU - Chen, J.

AU - Chen, J. H.

AU - Chen, Q.

AU - Chen, Z.

AU - Cheng, J.

AU - Cheng, Y.

AU - Christie, W.

AU - Chu, X.

AU - Corey, S.

AU - Crawford, H. J.

AU - Csanád, M.

AU - Dale-Gau, G.

AU - Das, A.

AU - Deppner, I. M.

AU - Deshpande, A.

AU - Dhamija, A.

PY - 2025/8/15

Y1 - 2025/8/15

N2 - Partonic collectivity is one of the necessary signatures for the formation of quark-gluon plasma in high-energy nuclear collisions. Number of constituent quarks (NCQ) scaling has been observed for hadron elliptic flow v2 in top energy nuclear collisions at the Relativistic Heavy Ion Collider and the LHC, and this has been theoretically suggested as strong evidence for partonic collectivity. In this Letter, a systematic analysis of v2 of π±, K±, KS0, p, and Λ in Au+Au collisions at sNN=3.2, 3.5, 3.9, and 4.5 GeV, with the STAR experiment at the Relativistic Heavy Ion Collider, is presented. NCQ scaling is markedly violated at 3.2 GeV, consistent with a hadronic-interaction dominated equation of state. However, as the collision energy increases, a gradual evolution to NCQ scaling is observed. This beam-energy dependence of v2 for all hadrons studied provides evidence for the onset of dominant partonic interactions by sNN=4.5 GeV.

AB - Partonic collectivity is one of the necessary signatures for the formation of quark-gluon plasma in high-energy nuclear collisions. Number of constituent quarks (NCQ) scaling has been observed for hadron elliptic flow v2 in top energy nuclear collisions at the Relativistic Heavy Ion Collider and the LHC, and this has been theoretically suggested as strong evidence for partonic collectivity. In this Letter, a systematic analysis of v2 of π±, K±, KS0, p, and Λ in Au+Au collisions at sNN=3.2, 3.5, 3.9, and 4.5 GeV, with the STAR experiment at the Relativistic Heavy Ion Collider, is presented. NCQ scaling is markedly violated at 3.2 GeV, consistent with a hadronic-interaction dominated equation of state. However, as the collision energy increases, a gradual evolution to NCQ scaling is observed. This beam-energy dependence of v2 for all hadrons studied provides evidence for the onset of dominant partonic interactions by sNN=4.5 GeV.

UR - https://www.scopus.com/pages/publications/105015680989

U2 - 10.1103/2qhx-cp79

DO - 10.1103/2qhx-cp79

M3 - Article

C2 - 40929191

AN - SCOPUS:105015680989

SN - 0031-9007

VL - 135

JO - Physical Review Letters

JF - Physical Review Letters

IS - 7

M1 - 072301

ER -

Onset of Constituent Quark Number Scaling in Heavy-Ion Collisions at RHIC

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