Experimental evidences of hydrodynamic flowin high-energy heavy-ion collisions	
ShinIchi Esumi, Inst. of Physics, Univ. of TsukubaØ Center for Integrated Research in Fundamental
Science and Engineering (CiRfSE)Ø Research Core for the History of the Universe(experimental elementary particle, nuclear physicsand cosmology groups)
Ø Division of Quark Nuclear Matters

Univ. of Tsukuba	Contents

LHC	
RHIC
J-PARC
FAIR,NICA

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

• connection between radial andelliptic flows• from partonic to hadronicsystem• possible flow in small and highdense system• relation to the critical point

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

1	Experiments at RHIC and LHC	ALICE	PHENIX	ATLAS	STAR	CMS	ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

2	

CMS	  STAR	  A+A central collision
A few – 10k particles in an event	

PHENIX	  ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

3	History of Temperature

QGP	

Initial Temperature	Chemical Freeze-out	Phase Transition	
Thermal Freeze-out	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

4	Thermal Freeze-out

collectiveexpansion[at the end of elastic collisions]
Momentum distributions are determinedwith freeze-out temperature Tfo andcollective radial expansion <bT>

transverse mass distribution	
ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

locally
thermalTeff = Tfo + 0.5 m 〈 v⊥ 〉 2
ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

5	

Hadron spectra at sqrt(sNN)=11.5 GeV	
central	peripheral	

STAR	ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

6	Strangeness Quark
pT distribution

based	  on	  Quark	  Coalescence	  picture 	  Ω(sss)	  /	  φ(ss)	  ~	  s	  quark	  yield	  arXiv:1506.07605, STAR	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

7	Charged particle multiplicity (Y = dNch/dη) 	
R = (Y/NPart) / (Y/NPart)central

QM14, PHENIX	

R = (Y/NQuark-Part) / (Y/NQuark-Part)central	

NQuark-­‐Part	NPart	
Nucleon	  picture	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

Npart + Ncoll explanation
nucleon or quark participant?	

Quark	  	  picture	
ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

8	Reaction Plane : Event Plane
beam view	

RXN-­‐detector	  	  (phenix)	
azimuthal angle
of ith particle 	
φiy

Φ2x

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

9	

2nd order event anisotropy v2 (Elliptic flow, Elliptic emission)
pyy! = atanpx

x"=y2 # x2

v2 =y2 + x2

Geometrical anisotropy	pxpx2 " py2
px2 + py2

Momentum anisotropy	!

!

-π
ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	py0

πφparticle-ΦR.P. (rad)ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

10	pT and particle mass dependence of v2

200GeV	  Au+Au,	  STAR	

v2	

BaryonMeson	

mass	  dependence	lines :
Hydrodynamic model
calculation for various
mass particles
ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	(qqq)	(qq)	pT (GeV/c)	

mT – m (GeV/c2)	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

11	Constituent Quark Number Scaling in v2	nq	  2	  2	  2	  3	  6	  PRL99(2007)052301	

Hadron	

Scaled bynumber of quark	

indication of v2
formation during
partonic phase	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

12	

Deviation from (Quark Number) mT Scaling --- radial expansion ---	
Au+Au 39GeV

Au+Au 200GeV

Pb+Pb 2.76TeV

40-45%

protonprotonPHENIX Preliminary

PHENIX Preliminary
M. Krzewicki, QM11
J. Phys. G38, (2011) 124047

roughly (mT-m0)/nq scaled for all energies
larger pT shift for heavier particlesradial flow increases with energy
elliptic and radial flows develop in different time scale
ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

13	High precision v2 measurements

arXiv:1405.4632	

at RHIC and LHC• High	  sta]s]cs	  measurements	  allow	  	  a	  precise	  comparison	  of	  v2(p)	  and	  v2(φ).	  	  • Some	  small	  devia]on	  from	  hydro-­‐like	  	  mass	  dependence	  of	  v2	  at	  low	  pT,	  that	  is	  expected	  by	  small	  hadronic	  cross	  sec]on	  of	  φ-­‐meson	  than	  that	  of	  proton.	  	  

qq
qqq	

200GeV Au+Au	

baryon	meson	
2.76TeV Pb+Pb	
pT (GeV/c)	
sssss	

baryon	meson	
Number	  of	  quark	  scaling	  	  as	  a	  signal	  of	  partonic	  phase	STAR,	  QM14	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

14	

Triangular expansion / geometryvn	

Elliptic and Triangular expansion : v2, v3	

Elliptic and Triangular shape : RHBTΦ2, RHBTΦ3	n=2	
n=3	
n=2	

PHENIX,	  QM12	  n=3	pT [GeV/c]	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

PRL112	  (2014)	  222301	  	ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

15	

εfinal via HBT interferometry	

Event	  Shape	  Engineering Q2	  (∼v2)	  ε2ﬁnal	  rela]on	  of	  ε2ini]al	  –	  v2	  –	  ε2ﬁnal	  for	  a	  given	  centrality	  PHENIX,	  QM14	  R.P. dependence of correlation	
1/Ntrig dNPair/dΔφ	2-­‐par]cle	  correla]on	

PHENIX
preliminary	

-1
ATLAS,	  QM14	  ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

01PHENIX,	  QM12	  234	-1

01234	Δφ = φAsso. – φTrig.	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

16	Cross harmonics correlation with Q2 selection
v2(Low pT) vs v2(high pT)v2 vs v3

ATLAS,	  QM14	  ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

17	Event Shape Engineering--- Test in ALICE experiment --( arXiv:1507.06194 ) 	

Glauber simulation
ρ - ε correlation
βT - v2 correlation	

flat pT dependence ~ 5GeV/c
confirmation of initial geometry selection	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

increased radial flow
+0.41% in βT for large Q2 event	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

18	High pT direct photon as penetrating probe	γ	pT	  >	  5	  GeV/c	 hadron	

γdir	

RAA	

< 1	∼ 1	v2	> 0	∼ 0	π0	  PRL 109 (2012) 152302

RAA	  
	  	  	  	  	  (surface)	

PRL 109 (2012) 122302

v2	

N (A+A)	  RAA	  =	  	 	  Ncoll	  N(p+p)	  π0	γinc	γdir	

rela]ve	  yield	  with	  respect	  to	  a	  simple	  independent	  superposi]on	  of	  pp	  data	  2.76TeV	  Pb+Pb	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

19	γ	

Direct Thermal Photon
Direct	  (thermal)	  photon,	  200GeV	  Au+Au,	  	  RHIC-­‐PHENIX,	  arXiv:1509.07758	

π0	  	  	  (surface)	

AuAu	
pp	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

20	

CMS	

Small, but high density systemp+p	

p+p	  H.M.	

p+p	

A+A	

ridge	
Jet2	

Jet1	
beam	

p+Pb	
ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ridge	

Pb+Pb	ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

21	Hydrodynamic collectivity
in small system?	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  3He+Au	  	  	  	  	  	  	  	  	  	  	  Glauber	  model	  	  d+Au	

2nd	  half	  of	  RUN16	  at	  RHIC	  Energy	  scan	  with	  d+Au	  	  at	  20,	  39,	  62	  and	  200GeV	

new	  3He+Au	  collision	  data	  from	  RHIC-­‐RUN14	
PRL115(2015)142301	  	radial	  ﬂow	  eﬀect	  :	  larger	  for	  heavier	  mass	

PRL111(2013)212301	

peripheral	  subtrac]on	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

22	

DirectedFlowv1	an]-­‐	  ﬂow	

ﬂow	arXiv:1401.3043
PRL112 (2014) 16, 162301
ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

23	

Search for fluctuation
originating from Critical Point
Higher moment of conserved quantity(Net-Baryon distribution)

PRL	  112	  (2014)	  032302	

Correlation of this w.r.t. flow (e-by-e flow selection,larger sensitivity in “less flow” event?)	
ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

Baryon density frombeam energy scan,
20-200GeV Au+Au,
RHIC-STAR/PHENIX,
arXiv:1506.07834	

Change of correlation length
at phase boundary close to
the critical point
ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

24	Summary••••

connection between radial and elliptic flows
from partonic to hadronic system
possible flow in small and high-dense system
relation to the critical point

Back-­‐up	  slides	  follow…	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

25	lower	  energy	higher	  energy	

High-Temperature to High-Densitywith Beam Energy Scan 2 at STAR	BES2	  program	  Au+Au	  5-­‐20	  GeV	  	  2019	  -­‐	  2020	

FAIR	  /	  J-­‐PARC	  Cri]cal	  Point	  ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

26	Chemical Freeze-out via thermal model fitting	[at the end ofinelastic collisions]
Particle yields and ratios
are determined withchemical freeze-outtemperature Tch andBaryon chemical
potential µB

High density region bylowering beam energy
Centrality dependence	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

27	Chemical Freeze-out model fitting	

ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

28	

φ-meson v2 --- a new puzzle ---• φ	  puzzle	  between	  central	  and	  peripheral	  at	  LHC	  • Extension	  of	  hydro-­‐dominant	  pT	  region	  w.r.t.	  hard	  contribu]on?	  	  2.75TeV	  Pb+Pb,	  ALICE	  arXiv:1405.4632	
ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

29	Temperature from Thermal Photon	
•

AuAu	

•
•

Virtual and real photon measurements via
internal and external conversion methods
with electron pair measurements
Real photon measurements with EMcal
Initial temperature of 300∼600MeV	
arXiv:1405.3940	
independent slope w.r.t. centrality	
yield ~ Npart1.5

dN / dy	pp	

Npart	ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	

30	

Direct (thermal) photon v2 and v3v2	v3	vn	  =	  <	  cos	  n(φ par]cle -­‐	  Φnplane)	  >	  (n=2	  :	  ellip]c	  ﬂow),	  (n=3	  :	  triangular	  ﬂow)	

v2	

v3	

arXiv	  :	  1509.07758	  	• comparable	  to	  hadron	  for	  both	  v2	  and	  v3	  at	  2∼3GeV/c	  • signiﬁcant	  contribu]on	  from	  photons	  from	  later	  stages	  	  (inconsistent	  with	  early	  photons	  from	  homer	  period)	  • ﬂamer	  pT	  dependence	  of	  v2	  at	  low	  pT	  ATHIC2016,	  15-­‐19/Feb/2016,	  New	  Delhi,	  India	

ShinIchi	  Esumi,	  Univ.	  of	  Tsukuba	31