1. PHENIX Measurements of Azimuthal Anisotropy at RHIC
Arkadiy Taranenko
National Research Nuclear University MEPhI (Moscow Engineering Physics Institute)
for the PHENIX Collaboration
The XXIII International Workshop  High Energy Physics and Quantum Field Theory
June 26– July 3,  2017
Yaroslavl, Russia

2. Azimuthal Anisotropy Measurements at PHENIX
Motivation
Methods : Vn measurements in PHENIX
System size dependence of anisotropy in small systems
PID Vn results in small systems at RHIC
Beam energy scan for d+Au collisions at RHIC
Summary ε2 ε3 ε4

3. The QGP Discovered at RHIC: 2005-2006
M. Roirdan and W. Zajc, Scientific American, May 2006

4. Anisotropic Flow in Heavy-Ion Collisions - methods
CMS
Different methods, non-flow, fluctuations

5. Anisotropic Flow in HIC at RHIC: results
n=2 for mesons
and
n=3 for baryons
PoS 2006 (2006) 021
Gale, Jeon, et al., Phys. Rev. Lett. 110,
Phys. Rev.C (R) 5

6. Collectivity in Small Colliding Systems?
Initial state
Pre-equillibrium
Quark Gluon Plasma?
Hadronization
Hadronic phase
and freezeout
QGP?
Final state interactions: Hydrodynamic Flow?
Initial momentum correlations: CGC?
How to distinguish initial vs final state effects ?
PLB 718 (2013) 795
PRL 115 (2015)
PLB 726 (2013) 164

7. PHENIX Experiment at RHIC
ZDC |η|>5.9
MPC/MPC-EX/ 7

8. PHENIX Flow Measurements : Methods
Central Arms (CA) |η’| < 0.35
(particle detection)
ψn RXN (|h|=1.0~2.8)
MPC (|h|=3.1~3.7)
BBC (|h|=3.1~3.9)
From 2012:
- FVTX (1.0<|h|<3)
Correlate hadrons in central Arms
with event plane (RXN, etc)
∆φ correlation function for EPN - EPS
(II)
(I)
∆φ correlation function for EP - CA

9. PHENIX Flow Measurements : Methods
Vn (EP): Phys.Rev.Lett. 107 (2011)   
Phys. Rev. Lett. 105, (2010)
Good agreement between Vn results obtained by event plane (EP) and two-particle correlation method (2PC)
No evidence for significant η-dependent non-flow contributions from di-jets for pT= GeV/c. Systematic uncertainty : event plane: 2-5% for v2 and 5-12% for v3.
ψn RXN (|h|=1.0~2.8)
MPC (|h|=3.1~3.7)
BBC (|h|=3.1~3.9)

10. Small system program at RHIC
HeAu
pAl
pAu
dAu
Geometry Scan
Different initial geometry  different final state particle emission for p+Au, d+Au and 3He+Au collisions
0-5% p+Au
0-5% d+Au
0-5% He+Au 2
0.23
0.54
0.50 3
0.16
0.19
0.28

11. Small system program at RHIC
HeAu
pAl
pAu
dAu
Geometry Scan
dAu 200GeV
Beam Energy Scan (BES) will help us to search for the turning off the QGP signatures
dAu 39GeV
dAu 62.4GeV
0-5% p+Au
0-5% d+Au
0-5% He+Au 2
0.23
0.54
0.50 3
0.16
0.19
0.28
dAu 19.6GeV
Energy Scan 11

12. Ridge in small systems ( 200 GeV)12
The near side long-range angular correlation (“ridge”) is observed in small systems for high multiplicity d+Au and 3He+Au events

13. Estimation of Non-Flow
Estimating Non-Flow
Estimation of Non-Flow
c2 (pT) = c2Non-Elementary + c2Elementary
c2 (pT) = c2Non-Elementary + c2p+p x
Charge at Forward h in p+p
Charge at Forward h in p+Au
v2: 7% in 3He+Au,10% in d+Au; 25% in p+Au  increases in smaller systems
v3 : 15% in 3He+Au
cited as a systematic uncertainty 13

14. Vn in small systems ( 200 GeV)
v2(3HeAu) ~ v2(dAu) > v2(pAu) ~ v2(pAl)
v3(3HeAu) > v3(dAu)
Hierarchy compatible with initial geometry + final state effects

15. Comparison with viscous hydro calculations
Hydro without preflow (SONIC)
Better describes the data
Hydro with preflow (super SONIC) over estimates v3 and v2 15

16. Identified particles v2
A clear mass ordering is seen in d/3He+Au collision while not in p+Au
A stronger radial flow in d/3He+Au?

17. Identified particle v2 comparison with hydro
p+Au
d+Au
3He+Au
Well described p/d/3He+Au results at low pT
Smaller mass split for v2 in p+Au is predicted
High pT data are not reproduced - recombination not included

18. Number of Quark Scaling in central 3He+Au
The familiar behavior of number of quark scaling observed in Au+Au collisions is also seen in the small 3He+Au system

19. V2 vs collision energy in d+Au
The v2 in 62.4 and 200 GeV dAu collisions are very similar
At lower collision energy, the v2 increase at high pT which may due to large non-flow

20. V2 vs collision energy in Au+Au
10-20 %
20-30 %
30-40 %
40-50 %

21. Comparison with viscous Hydro.
Both SONIC and super SONIC calculations are lower than measurements at lower collision energies. It further indicates the large non-flow

22. √s dependence of c2{4} at RHIC
Surprising features: v2{4} larger at lower √s, reaching v2{2}.
Difficult to describe in both CGC and hydro
Important to understand non-flow in standard cumulant method

23. Summary
By scanning different colliding systems PHENIX found that the initial geometry play an important roles for the ridge and vn in small systems. And these results can be well described by the viscous hydro calculations. RHIC geometry scan suggest ordering of vn follows that of εn.
The mass ordering, NCQ scaling and four particles cumulant results indicate a collective behavior in small systems
The v2 has been measure in small system from 200 GeV to GeV by event plane method, but nonflow effect need to be further studied
v2{4} larger at lower √s, reaching v2{2}.

24. Backup Slides 24