System-size independence of directed flow measured at the BNL relativistic heavy-ion collider.
We measure directed flow (v_{1}) for charged particles in Au+Au and Cu+Cu collisions at sqrt[s_{NN}]=200 and 62.4 GeV, as a function of pseudorapidity (eta), transverse momentum (p_{t}), and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all available model implementations, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to v_{1} in different collision systems, and investigate possible explanations for the observed sign change in v_{1}(p_{t}).
Abelev
B I
BI
University of Illinois at Chicago, Chicago, Illinois 60607, USA.
Aggarwal
M M
MM
Ahammed
Z
Z
Anderson
B D
BD
Arkhipkin
D
D
Averichev
G S
GS
Bai
Y
Y
Balewski
J
J
Barannikova
O
O
Barnby
L S
LS
Baudot
J
J
Baumgart
S
S
Beavis
D R
DR
Bellwied
R
R
Benedosso
F
F
Betts
R R
RR
Bhardwaj
S
S
Bhasin
A
A
Bhati
A K
AK
Bichsel
H
H
Bielcik
J
J
Bielcikova
J
J
Biritz
B
B
Bland
L C
LC
Bombara
M
M
Bonner
B E
BE
Botje
M
M
Bouchet
J
J
Braidot
E
E
Brandin
A V
AV
Bueltmann
S
S
Burton
T P
TP
Bystersky
M
M
Cai
X Z
XZ
Caines
H
H
Calderón de la Barca Sánchez
M
M
Callner
J
J
Catu
O
O
Cebra
D
D
Cendejas
R
R
Cervantes
M C
MC
Chajecki
Z
Z
Chaloupka
P
P
Chattopadhyay
S
S
Chen
H F
HF
Chen
J H
JH
Chen
J Y
JY
Cheng
J
J
Cherney
M
M
Chikanian
A
A
Choi
K E
KE
Christie
W
W
Chung
S U
SU
Clarke
R F
RF
Codrington
M J M
MJ
Coffin
J P
JP
Cormier
T M
TM
Cosentino
M R
MR
Cramer
J G
JG
Crawford
H J
HJ
Das
D
D
Dash
S
S
Daugherity
M
M
de Moura
M M
MM
Dedovich
T G
TG
Dephillips
M
M
Derevschikov
A A
AA
Derradi de Souza
R
R
Didenko
L
L
Dietel
T
T
Djawotho
P
P
Dogra
S M
SM
Dong
X
X
Drachenberg
J L
JL
Draper
J E
JE
Du
F
F
Dunlop
J C
JC
Dutta Mazumdar
M R
MR
Edwards
W R
WR
Efimov
L G
LG
Elhalhuli
E
E
Elnimr
M
M
Emelianov
V
V
Engelage
J
J
Eppley
G
G
Erazmus
B
B
Estienne
M
M
Eun
L
L
Fachini
P
P
Fatemi
R
R
Fedorisin
J
J
Feng
A
A
Filip
P
P
Finch
E
E
Fine
V
V
Fisyak
Y
Y
Gagliardi
C A
CA
Gaillard
L
L
Gangadharan
D R
DR
Ganti
M S
MS
Garcia-Solis
E
E
Ghazikhanian
V
V
Ghosh
P
P
Gorbunov
Y N
YN
Gordon
A
A
Grebenyuk
O
O
Grosnick
D
D
Grube
B
B
Guertin
S M
SM
Guimaraes
K S F F
KS
Gupta
A
A
Gupta
N
N
Guryn
W
W
Haag
B
B
Hallman
T J
TJ
Hamed
A
A
Harris
J W
JW
He
W
W
Heinz
M
M
Heppelmann
S
S
Hippolyte
B
B
Hirsch
A
A
Hoffman
A M
AM
Hoffmann
G W
GW
Hofman
D J
DJ
Hollis
R S
RS
Huang
H Z
HZ
Hughes
E W
EW
Humanic
T J
TJ
Igo
G
G
Iordanova
A
A
Jacobs
P
P
Jacobs
W W
WW
Jakl
P
P
Jin
F
F
Jones
P G
PG
Judd
E G
EG
Kabana
S
S
Kajimoto
K
K
Kang
K
K
Kapitan
J
J
Kaplan
M
M
Keane
D
D
Kechechyan
A
A
Kettler
D
D
Khodyrev
V Yu
VY
Kiryluk
J
J
Kisiel
A
A
Klein
S R
SR
Knospe
A G
AG
Kocoloski
A
A
Koetke
D D
DD
Kollegger
T
T
Kopytine
M
M
Kotchenda
L
L
Kouchpil
V
V
Kravtsov
P
P
Kravtsov
V I
VI
Krueger
K
K
Kuhn
C
C
Kumar
A
A
Kumar
L
L
Kurnadi
P
P
Lamont
M A C
MA
Landgraf
J M
JM
Lange
S
S
Lapointe
S
S
Laue
F
F
Lauret
J
J
Lebedev
A
A
Lednicky
R
R
Lee
C-H
CH
Levine
M J
MJ
Li
C
C
Li
Y
Y
Lin
G
G
Lin
X
X
Lindenbaum
S J
SJ
Lisa
M A
MA
Liu
F
F
Liu
J
J
Liu
L
L
Ljubicic
T
T
Llope
W J
WJ
Longacre
R S
RS
Love
W A
WA
Lu
Y
Y
Ludlam
T
T
Lynn
D
D
Ma
G L
GL
Ma
J G
JG
Ma
Y G
YG
Mahapatra
D P
DP
Majka
R
R
Mangotra
L K
LK
Manweiler
R
R
Margetis
S
S
Markert
C
C
Matis
H S
HS
Matulenko
Yu A
YA
McShane
T S
TS
Meschanin
A
A
Millane
J
J
Miller
M L
ML
Minaev
N G
NG
Mioduszewski
S
S
Mischke
A
A
Mitchell
J
J
Mohanty
B
B
Morozov
D A
DA
Munhoz
M G
MG
Nandi
B K
BK
Nattrass
C
C
Nayak
T K
TK
Nelson
J M
JM
Nepali
C
C
Netrakanti
P K
PK
Ng
M J
MJ
Nogach
L V
LV
Nurushev
S B
SB
Odyniec
G
G
Ogawa
A
A
Okada
H
H
Okorokov
V
V
Olson
D
D
Pachr
M
M
Pal
S K
SK
Panebratsev
Y
Y
Pawlak
T
T
Peitzmann
T
T
Perevoztchikov
V
V
Perkins
C
C
Peryt
W
W
Phatak
S C
SC
Planinic
M
M
Pluta
J
J
Poljak
N
N
Porile
N
N
Poskanzer
A M
AM
Potekhin
M
M
Potukuchi
B V K S
BV
Prindle
D
D
Pruneau
C
C
Pruthi
N K
NK
Putschke
J
J
Qattan
I A
IA
Raniwala
R
R
Raniwala
S
S
Ray
R L
RL
Ridiger
A
A
Ritter
H G
HG
Roberts
J B
JB
Rogachevskiy
O V
OV
Romero
J L
JL
Rose
A
A
Roy
C
C
Ruan
L
L
Russcher
M J
MJ
Rykov
V
V
Sahoo
R
R
Sakrejda
I
I
Sakuma
T
T
Salur
S
S
Sandweiss
J
J
Sarsour
M
M
Schambach
J
J
Scharenberg
R P
RP
Schmitz
N
N
Seger
J
J
Selyuzhenkov
I
I
Seyboth
P
P
Shabetai
A
A
Shahaliev
E
E
Shao
M
M
Sharma
M
M
Shi
S S
SS
Shi
X-H
XH
Sichtermann
E P
EP
Simon
F
F
Singaraju
R N
RN
Skoby
M J
MJ
Smirnov
N
N
Snellings
R
R
Sorensen
P
P
Sowinski
J
J
Spinka
H M
HM
Srivastava
B
B
Stadnik
A
A
Stanislaus
T D S
TD
Staszak
D
D
Stock
R
R
Strikhanov
M
M
Stringfellow
B
B
Suaide
A A P
AA
Suarez
M C
MC
Subba
N L
NL
Sumbera
M
M
Sun
X M
XM
Sun
Y
Y
Sun
Z
Z
Surrow
B
B
Symons
T J M
TJ
Szanto de Toledo
A
A
Takahashi
J
J
Tang
A H
AH
Tang
Z
Z
Tarnowsky
T
T
Thein
D
D
Thomas
J H
JH
Tian
J
J
Timmins
A R
AR
Timoshenko
S
S
Tokarev
M
M
Trainor
T A
TA
Tram
V N
VN
Trattner
A L
AL
Trentalange
S
S
Tribble
R E
RE
Tsai
O D
OD
Ulery
J
J
Ullrich
T
T
Underwood
D G
DG
Van Buren
G
G
van der Kolk
N
N
van Leeuwen
M
M
Vander Molen
A M
AM
Varma
R
R
Vasconcelos
G M S
GM
Vasilevski
I M
IM
Vasiliev
A N
AN
Videbaek
F
F
Vigdor
S E
SE
Viyogi
Y P
YP
Vokal
S
S
Voloshin
S A
SA
Wada
M
M
Waggoner
W T
WT
Wang
F
F
Wang
G
G
Wang
J S
JS
Wang
Q
Q
Wang
X
X
Wang
X L
XL
Wang
Y
Y
Webb
J C
JC
Westfall
G D
GD
Whitten
C
C
Wieman
H
H
Wissink
S W
SW
Witt
R
R
Wu
J
J
Wu
Y
Y
Xu
N
N
Xu
Q H
QH
Xu
Y
Y
Xu
Z
Z
Yang
Y Y
YY
Yepes
P
P
Yoo
I-K
IK
Yue
Q
Q
Zawisza
M
M
Zbroszczyk
H
H
Zhan
W
W
Zhang
H
H
Zhang
S
S
Zhang
W M
WM
Zhang
Y
Y
Zhang
Z P
ZP
Zhao
Y
Y
Zhong
C
C
Zhou
J
J
Zoulkarneev
R
R
Zoulkarneeva
Y
Y
Zuo
J X
JX