Measurement of directed flow in Au + Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV with the STAR event plane detector

M. I. Abdulhamid; B. E. Aboona; J. Adam; L. Adamczyk; J. R. Adams; I. Aggarwal; M. M. Aggarwal; Z. Ahammed; E. C. Aschenauer; S. Aslam; J. Atchison; V. Bairathi; J. G. Ball Cap; K. Barish; R. Bellwied; P. Bhagat; A. Bhasin; S. Bhatta; S. R. Bhosale; J. Bielcik; J. Bielcikova; J. D. Brandenburg; C. Broodo; X. Z. Cai; H. Caines; M. Calderón de la Barca Sánchez; D. Cebra; J. Ceska; I. Chakaberia; P. Chaloupka; B. K. Chan; Z. Chang; A. Chatterjee; D. Chen; J. Chen; J. H. Chen; Z. Chen; J. Cheng; Y. Cheng; W. Christie; X. Chu; H. J. Crawford; M. Csanád; G. Dale-Gau; A. Das; I. M. Deppner; A. Dhamija; P. Dixit; X. Dong; J. L. Drachenberg; E. Duckworth; J. C. Dunlop; J. Engelage; G. Eppley; S. Esumi; O. Evdokimov; O. Eyser; R. Fatemi; S. Fazio; C. J. Feng; Y. Feng; E. Finch; Y. Fisyak; F. A. Flor; C. Fu; C. A. Gagliardi; T. Galatyuk; T. Gao; F. Geurts; N. Ghimire; A. Gibson; K. Gopal; X. Gou; D. Grosnick; A. Gupta; W. Guryn; A. Hamed; Y. Han; S. Harabasz; M. D. Harasty; J. W. Harris; H. Harrison-Smith; W. He; X. H. He; Y. He; N. Herrmann; L. Holub; C. Hu; Q. Hu; Y. Hu; H. Huang; H. Z. Huang; S. L. Huang; T. Huang; Y. Huang; T. J. Humanic; M. Isshiki; W. W. Jacobs; A. Jalotra; C. Jena; A. Jentsch; Y. Ji; J. Jia; C. Jin; X. Ju; E. G. Judd; S. Kabana; D. Kalinkin; K. Kang; D. Kapukchyan; K. Kauder; D. Keane; A. Khanal; Y. V. Khyzhniak; D. P. Kikoła; D. Kincses; I. Kisel; A. Kiselev; A. G. Knospe; H. S. Ko; J. Kołaś; L. K. Kosarzewski; L. Kumar; M. C. Labonte; R. Lacey; J. M. Landgraf; J. Lauret; A. Lebedev; J. H. Lee; Y. H. Leung; C. Li; D. Li; H.-S. Li; H. Li; W. Li; X. Li; Y. Li; Z. Li; X. Liang; Y. Liang; R. Licenik; T. Lin; Y. Lin; M. A. Lisa; C. Liu; G. Liu; H. Liu; L. Liu; T. Liu; X. Liu; Y. Liu; Z. Liu; T. Ljubicic; O. Lomicky; R. S. Longacre; E. M. Loyd; T. Lu; J. Luo; X. F. Luo; L. Ma; R. Ma; Y. G. Ma; N. Magdy; D. Mallick; R. Manikandhan; S. Margetis; C. Markert; O. Matonoha; G. McNamara; O. Mezhanska; K. Mi; S. Mioduszewski; B. Mohanty; B. Mondal; M. M. Mondal; I. Mooney; J. Mrazkova; M. I. Nagy; A. S. Nain; J. D. Nam; M. Nasim; D. Neff; J. M. Nelson; M. Nie; G. Nigmatkulov; T. Niida; T. Nonaka; G. Odyniec; A. Ogawa; S. Oh; K. Okubo; B. S. Page; S. Pal; A. Pandav; A. Panday; A. K. Pandey; T. Pani; A. Paul; B. Pawlik; D. Pawlowska; C. Perkins; J. Pluta; B. R. Pokhrel; M. Posik; T. L. Protzman; V. Prozorova; N. K. Pruthi; M. Przybycien; J. Putschke; Z. Qin; H. Qiu; C. Racz; S. K. Radhakrishnan; A. Rana; R. L. Ray; R. Reed; C. W. Robertson; M. Robotkova; M. A. Rosales Aguilar; D. Roy; P. Roy Chowdhury; L. Ruan; A. K. Sahoo; N. R. Sahoo; H. Sako; S. Salur; S. Sato; B. C. Schaefer; W. B. Schmidke; N. Schmitz; F.-J. Seck; J. Seger; R. Seto; P. Seyboth; N. Shah; P. V. Shanmuganathan; T. Shao; M. Sharma; N. Sharma; R. Sharma; S. R. Sharma; A. I. Sheikh; D. Shen; D. Y. Shen; K. Shen; S. S. Shi; Y. Shi; Q. Y. Shou; F. Si; J. Singh; S. Singha; P. Sinha; M. J. Skoby; N. Smirnov; Y. Söhngen; Y. Song; B. Srivastava; T. D. S. Stanislaus; M. Stefaniak; D. J. Stewart; Y. Su; M. Sumbera; C. Sun; X. Sun; Y. Sun; B. Surrow; M. Svoboda; Z. W. Sweger; A. C. Tamis; A. H. Tang; Z. Tang; T. Tarnowsky; J. H. Thomas; A. R. Timmins; D. Tlusty; T. Todoroki; S. Trentalange; P. Tribedy; S. K. Tripathy; T. Truhlar; B. A. Trzeciak; O. D. Tsai; C. Y. Tsang; Z. Tu; J. Tyler; T. Ullrich; D. G. Underwood; I. Upsal; G. Van Buren; J. Vanek; I. Vassiliev; V. Verkest; F. Videbæk; S. A. Voloshin; G. Wang; J. S. Wang; J. Wang; K. Wang; X. Wang; Y. Wang; Z. Wang; J. C. Webb; P. C. Weidenkaff; G. D. Westfall; D. Wielanek; H. Wieman; G. Wilks; S. W. Wissink; R. Witt; J. Wu; X. Wu; B. Xi; Z. G. Xiao; G. Xie; W. Xie; H. Xu; N. Xu; Q. H. Xu; Y. Xu; Z. Xu; G. Yan; Z. Yan; C. Yang; Q. Yang; S. Yang; Y. Yang; Z. Ye; L. Yi; Y. Yu; H. Zbroszczyk; W. Zha; C. Zhang; D. Zhang; J. Zhang; S. Zhang; W. Zhang; X. Zhang; Y. Zhang; Z. J. Zhang; Z. Zhang; F. Zhao; J. Zhao; M. Zhao; S. Zhou; Y. Zhou; X. Zhu; M. Zurek; M. Zyzak; The Ohio State University, Columbus, OH (United States)

doi:10.1103/PhysRevC.111.014906

$Measurement of directed flow in Au + Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV with the STAR event plane detector$

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Peer reviewed

Measurement of directed flow in Au + Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV with the STAR event plane detector

M. I. Abdulhamid, B. E. Aboona, J. Adam, L. Adamczyk, J. R. Adams, I. Aggarwal, M. M. Aggarwal, Z. Ahammed, E. C. Aschenauer, S. Aslam, …

Physical review. C, Vol.111(1)

01/09/2025

DOI: https://doi.org/10.1103/PhysRevC.111.014906

Abstract

Collective flow

QCD phase transitions

Quark-gluon plasma

Relativistic heavy-ion collisions

In heavy-ion collision experiments, the global collectivity of final-state particles can be quantified by anisotropic flow coefficients (𝑣𝑛). The first-order flow coefficient, also referred to as the directed flow (𝑣1), describes the collective sideward motion of produced particles and nuclear fragments in heavy-ion collisions. It carries information on the very early stage of the collision, especially at large pseudorapidity (𝜂), where it is believed to be generated during the nuclear passage time. Directed flow therefore probes the onset of bulk collective dynamics during thermalization, providing valuable experimental guidance to models of the pre-equilibrium stage. In 2018, the Event Plane Detector (EPD) was installed in STAR and used for the Beam Energy Scan phase-II (BES-II) data taking. The combination of EPD (2.1 < |𝜂| < 5.1) and high-statistics BES-II data enables us to extend the 𝑣1 measurement to the forward and backward 𝜂 regions. In this paper, we present the measurement of 𝑣1 over a wide 𝜂 range in Au + Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV using the STAR EPD. The results of the analysis at $\sqrt{s_{NN}}$ = 19.6 GeV exhibit excellent consistency with the previous PHOBOS measurement, while elevating the precision of the overall measurement. The increased precision of the measurement also revealed finer structures in heavy-ion collisions, including a potential observation of the first-order event-plane decorrelation. Multiple physics models were compared to the experimental results. Only a transport model and a three-fluid hybrid model can reproduce a sizable 𝑣1 at large 𝜂 as was observed experimentally. The model comparison also indicates 𝑣1 at large 𝜂 might be sensitive to the QGP phase transition.

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Title: Measurement of directed flow in Au + Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV with the STAR event plane detector
Creators: M. I. Abdulhamid - American University in Cairo
B. E. Aboona - Mitchell Institute
J. Adam - Czech Technical University in Prague
L. Adamczyk - AGH University of Krakow
J. R. Adams - The Ohio State University
I. Aggarwal - Panjab University
M. M. Aggarwal - Panjab University
Z. Ahammed - Variable Energy Cyclotron Centre
E. C. Aschenauer - Brookhaven National Laboratory
S. Aslam - Indian Institute Technology
J. Atchison - Abilene Christian University
V. Bairathi - Instituto de Alta Investigación
J. G. Ball Cap - University of Houston
K. Barish - University of California System
R. Bellwied - University of Houston
P. Bhagat - University of Jammu
A. Bhasin - University of Jammu
S. Bhatta - State University of New York
S. R. Bhosale - Eötvös Loránd University
J. Bielcik - Czech Technical University in Prague
J. Bielcikova - Czech Academy of Sciences, Nuclear Physics Institute
J. D. Brandenburg - The Ohio State University
C. Broodo - University of Houston
X. Z. Cai - Shanghai Institute of Applied Physics
H. Caines - Yale University
M. Calderón de la Barca Sánchez - University of California
D. Cebra - University of California System
J. Ceska - Czech Technical University in Prague
I. Chakaberia - Lawrence Berkeley National Laboratory
P. Chaloupka - Czech Technical University in Prague
B. K. Chan - University of California System
Z. Chang - Indiana University
A. Chatterjee - National Institute of Technology Durgapur
D. Chen - University of California System
J. Chen - Shandong University
J. H. Chen - Shandong University
Z. Chen - Shandong University
J. Cheng - Tsinghua University
Y. Cheng - University of California System
W. Christie - Brookhaven National Laboratory
X. Chu - Brookhaven National Laboratory
H. J. Crawford - University of California System
M. Csanád - Eötvös Loránd University
G. Dale-Gau - University of Illinois Chicago
A. Das - Czech Technical University in Prague
I. M. Deppner - Heidelberg University
A. Dhamija - Panjab University
P. Dixit - Indian Institute of Science Education and Research Berhampur
X. Dong - Lawrence Berkeley National Laboratory
J. L. Drachenberg - Abilene Christian University
E. Duckworth - Kent State University
J. C. Dunlop - Brookhaven National Laboratory
J. Engelage - University of California System
G. Eppley - Rice University
S. Esumi - University of Tsukuba
O. Evdokimov - University of Illinois Chicago
O. Eyser - Brookhaven National Laboratory
R. Fatemi - University of Kentucky
S. Fazio - University of Calabria
C. J. Feng - National Cheng Kung University
Y. Feng - Purdue University West Lafayette
E. Finch - Southern Connecticut State University
Y. Fisyak - Brookhaven National Laboratory
F. A. Flor - Yale University
C. Fu - Institute of Modern Physics
C. A. Gagliardi - Mitchell Institute
T. Galatyuk - Technical University of Darmstadt
T. Gao - Shandong University
F. Geurts - Rice University
N. Ghimire - Temple College
A. Gibson - Valparaiso University
K. Gopal - Indian Institute of Science Education and Research, Tirupati
X. Gou - Shandong University
D. Grosnick - Valparaiso University
A. Gupta - University of Jammu
W. Guryn - Brookhaven National Laboratory
A. Hamed - American University in Cairo
Y. Han - Rice University
S. Harabasz - Technical University of Darmstadt
M. D. Harasty - University of California System
J. W. Harris - Yale University
H. Harrison-Smith - University of Kentucky
W. He - Fudan University
X. H. He - Institute of Modern Physics
Y. He - Shandong University
N. Herrmann - Heidelberg University
L. Holub - Czech Technical University in Prague
C. Hu - University of Chinese Academy of Sciences
Q. Hu - Institute of Modern Physics
Y. Hu - Panjab University
H. Huang - National Cheng Kung University
H. Z. Huang - National Cheng Kung University
S. L. Huang - State University of New York
T. Huang - University of Illinois Chicago
Y. Huang - Tsinghua University
Y. Huang - Tsinghua University
T. J. Humanic - The Ohio State University
M. Isshiki - University of Tsukuba
W. W. Jacobs - Indiana University
A. Jalotra - University of Jammu
C. Jena - Indian Institute of Science Education and Research (IISER) Tirupati
A. Jentsch - Brookhaven National Laboratory
Y. Ji - Lawrence Berkeley National Laboratory
J. Jia - State University of New York
C. Jin - Rice University
X. Ju - University of Science and Technology of China
E. G. Judd - University of California
S. Kabana - Instituto de Alta Investigación
D. Kalinkin - University of Kentucky
K. Kang - Tsinghua University
D. Kapukchyan - University of California
K. Kauder - Brookhaven National Laboratory
D. Keane - Kent State University
A. Khanal - Wayne State University
Y. V. Khyzhniak - The Ohio State University
D. P. Kikoła - Warsaw University of Technology
D. Kincses - Eötvös Loránd University
I. Kisel - Frankfurt Institute for Advanced Studies
A. Kiselev - Brookhaven National Laboratory
A. G. Knospe - Lehigh University
H. S. Ko - Lawrence Berkeley National Laboratory
J. Kołaś - Warsaw University of Technology
L. K. Kosarzewski - The Ohio State University
L. Kumar - Panjab University
M. C. Labonte - University of California
R. Lacey - State University of New York
J. M. Landgraf - Brookhaven National Laboratory
J. Lauret - Brookhaven National Laboratory
A. Lebedev - Brookhaven National Laboratory
J. H. Lee - Brookhaven National Laboratory
Y. H. Leung - Heidelberg
C. Li - Central China Normal University
D. Li - University of Science and Technology of China
H.-S. Li - Purdue University
H. Li - Wuhan University of Science and Technology
W. Li - Rice University
X. Li - University of Science and Technology of China
Y. Li - University of Science and Technology of China
Y. Li - Tsinghua University
Z. Li - University of Science and Technology of China
X. Liang - University of California
Y. Liang - Kent State University
R. Licenik - Czech Academy of Sciences, Nuclear Physics Institute
T. Lin - Shandong University
Y. Lin - Guangxi Normal University
M. A. Lisa - The Ohio State University
C. Liu - Institute of Modern Physics
G. Liu - South China Normal University
H. Liu - Central China Normal University
L. Liu - Central China Normal University
T. Liu - Yale University
X. Liu - The Ohio State University
Y. Liu - Texas A&M University
Z. Liu - Central China Normal University
T. Ljubicic - Rice University
O. Lomicky - Czech Technical University in Prague
R. S. Longacre - Brookhaven National Laboratory
E. M. Loyd - University of California
T. Lu - Institute of Modern Physics
J. Luo - University of Science and Technology of China
X. F. Luo - Central China Normal University
L. Ma - Fudan University
R. Ma - Brookhaven National Laboratory
Y. G. Ma - Fudan University
N. Magdy - State University of New York
D. Mallick - Warsaw University of Technology
R. Manikandhan - University of Houston
S. Margetis - Kent State University
C. Markert - University of Texas
O. Matonoha - Czech Technical University in Prague
G. McNamara - Wayne State University
O. Mezhanska - Czech Technical University in Prague
K. Mi - Central China Normal University
S. Mioduszewski - Texas A&M University
B. Mohanty - National Institute of Science Education and Research
B. Mondal - National Institute of Science Education and Research
M. M. Mondal - National Institute of Science Education and Research
I. Mooney - Yale University
J. Mrazkova - Czech Academy of Sciences, Nuclear Physics Institute
M. I. Nagy - Eötvös Loránd University
A. S. Nain - Panjab University
J. D. Nam - Temple University
M. Nasim - Indian Institute of Science Education and Research (IISER)
D. Neff - University of California
J. M. Nelson - University of California
M. Nie - Shandong University
G. Nigmatkulov - University of Illinois Chicago
T. Niida - University of Tsukuba
T. Nonaka - University of Tsukuba
G. Odyniec - Lawrence Berkeley National Laboratory
A. Ogawa - Brookhaven National Laboratory
S. Oh - Sejong University
K. Okubo - University of Tsukuba
B. S. Page - Brookhaven National Laboratory
S. Pal - Czech Technical University in Prague
A. Pandav - Lawrence Berkeley National Laboratory
A. Panday - Indian Institute of Science Education and Research (IISER)
A. K. Pandey - Institute of Modern Physics
T. Pani - Rutgers, The State University of New Jersey
A. Paul - University of California
B. Pawlik - Institute of Nuclear Physics PAN
D. Pawlowska - Warsaw University of Technology
C. Perkins - University of California
J. Pluta - Warsaw University of Technology
B. R. Pokhrel - Temple University
M. Posik - Temple University
T. L. Protzman - Lehigh University
V. Prozorova - Czech Technical University in Prague
N. K. Pruthi - Panjab University
M. Przybycien - AGH University of Krakow
J. Putschke - Wayne State University
Z. Qin - Tsinghua University
H. Qiu - Institute of Modern Physics
C. Racz - University of California
S. K. Radhakrishnan - Kent State University
A. Rana - Panjab University
R. L. Ray - University of Texas
R. Reed - Lehigh University
C. W. Robertson - Purdue University
M. Robotkova - Czech Academy of Sciences, Nuclear Physics Institute
M. A. Rosales Aguilar - University of Kentucky
D. Roy - Rutgers, The State University of New Jersey
P. Roy Chowdhury - Warsaw University of Technology
L. Ruan - Brookhaven National Laboratory
A. K. Sahoo - Indian Institute of Science Education and Research (IISER)
N. R. Sahoo - Indian Institute of Science Education and Research (IISER) Tirupati
H. Sako - University of Tsukuba
S. Salur - Rutgers, The State University of New Jersey
S. Sato - University of Tsukuba
B. C. Schaefer - Lehigh University
W. B. Schmidke - Brookhaven National Laboratory
N. Schmitz - Max
F.-J. Seck - Technische Universität Darmstadt
J. Seger - Creighton University
R. Seto - University of California
P. Seyboth - Max
N. Shah - Indian Institute Technology
P. V. Shanmuganathan - Brookhaven National Laboratory
T. Shao - Fudan University
M. Sharma - University of Jammu
N. Sharma - Indian Institute of Science Education and Research (IISER)
R. Sharma - Indian Institute of Science Education and Research (IISER) Tirupati
S. R. Sharma - Indian Institute of Science Education and Research (IISER) Tirupati
A. I. Sheikh - Kent State University
D. Shen - Shandong University
D. Y. Shen - Fudan University
K. Shen - University of Science and Technology of China
S. S. Shi - Central China Normal University
Y. Shi - Shandong University
Q. Y. Shou - Fudan University
F. Si - University of Science and Technology of China
J. Singh - Instituto de Alta Investigación
S. Singha - Institute of Modern Physics
P. Sinha - Indian Institute of Science Education and Research (IISER) Tirupati
M. J. Skoby
N. Smirnov - Yale University
Y. Söhngen - Heidelberg
Y. Song - Yale University
B. Srivastava - Purdue University
T. D. S. Stanislaus - Valparaiso University
M. Stefaniak - The Ohio State University
D. J. Stewart - Wayne State University
Y. Su - University of Science and Technology of China
M. Sumbera - Czech Academy of Sciences, Nuclear Physics Institute
C. Sun - State University of New York
X. Sun - Institute of Modern Physics
Y. Sun - University of Science and Technology of China
Y. Sun - Huzhou University
B. Surrow - Temple University
M. Svoboda - Czech Academy of Sciences, Nuclear Physics Institute
Z. W. Sweger - University of California
A. C. Tamis - Yale University
A. H. Tang - Brookhaven National Laboratory
Z. Tang - University of Science and Technology of China
T. Tarnowsky - Michigan State University
J. H. Thomas - Lawrence Berkeley National Laboratory
A. R. Timmins - University of Houston
D. Tlusty - Creighton University
T. Todoroki - University of Tsukuba
S. Trentalange - University of California
P. Tribedy - Brookhaven National Laboratory
S. K. Tripathy - Warsaw University of Technology
T. Truhlar - Czech Technical University in Prague
B. A. Trzeciak - Czech Technical University in Prague
O. D. Tsai
C. Y. Tsang - Brookhaven National Laboratory
Z. Tu - Brookhaven National Laboratory
J. Tyler - Texas A&M University
T. Ullrich - Brookhaven National Laboratory
D. G. Underwood
I. Upsal - University of Science and Technology of China
G. Van Buren - Brookhaven National Laboratory
J. Vanek - Brookhaven National Laboratory
I. Vassiliev - Frankfurt Institute for Advanced Studies
V. Verkest - Wayne State University
F. Videbæk - Brookhaven National Laboratory
S. A. Voloshin - Wayne State University
G. Wang - University of California
J. S. Wang - Huzhou University
J. Wang - Shandong University
K. Wang - University of Science and Technology of China
X. Wang - Shandong University
Y. Wang - University of Science and Technology of China
Y. Wang - Central China Normal University
Y. Wang - Tsinghua University
Z. Wang - Shandong University
J. C. Webb - Brookhaven National Laboratory
P. C. Weidenkaff - Heidelberg
G. D. Westfall - Michigan State University
D. Wielanek - Warsaw University of Technology
H. Wieman - Lawrence Berkeley National Laboratory
G. Wilks - University of Illinois Chicago
S. W. Wissink - Indiana University
R. Witt - United States Naval Academy
J. Wu - Central China Normal University
J. Wu - Institute of Modern Physics
X. Wu - University of California
X. Wu - University of Science and Technology of China
B. Xi - Fudan University
Z. G. Xiao - Tsinghua University
G. Xie - University of Chinese Academy of Sciences
W. Xie - Purdue University
H. Xu - Huzhou University
N. Xu - Lawrence Berkeley National Laboratory
Q. H. Xu - Shandong University
Y. Xu - Shandong University
Y. Xu - Central China Normal University
Z. Xu - Kent State University
Z. Xu - University of California
G. Yan - Shandong University
Z. Yan - State University of New York
C. Yang - Shandong University
Q. Yang - Shandong University
S. Yang - South China Normal University
Y. Yang - National Cheng Kung University
Z. Ye - South China Normal University
Z. Ye - Lawrence Berkeley National Laboratory
L. Yi - Shandong University
Y. Yu - Shandong University
H. Zbroszczyk - Warsaw University of Technology
W. Zha - University of Science and Technology of China
C. Zhang - Fudan University
D. Zhang - South China Normal University
J. Zhang - Shandong University
S. Zhang - Chongqing University
W. Zhang - South China Normal University
X. Zhang - Institute of Modern Physics
Y. Zhang - Institute of Modern Physics
Y. Zhang - University of Science and Technology of China
Y. Zhang - Shandong University
Y. Zhang - Guangxi Normal University
Z. J. Zhang - National Cheng Kung University
Z. Zhang - Brookhaven National Laboratory
Z. Zhang - University of Illinois Chicago
F. Zhao - Institute of Modern Physics
J. Zhao - Fudan University
M. Zhao - Brookhaven National Laboratory
S. Zhou - Central China Normal University
Y. Zhou - Central China Normal University
X. Zhu - Tsinghua University
M. Zurek
M. Zyzak - Frankfurt Institute for Advanced Studies
The Ohio State University, Columbus, OH (United States)
Publication Details: Physical review. C, Vol.111(1)
Publisher: American Physical Society (APS)
Identifiers: 991006241221702656
Academic Unit: Physics
Language: English
Resource Type: Journal article

Measurement of directed flow in Au + Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV with the STAR event plane detector

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