Latest results of charged hadron flow
measurements in CuAu collisions atRHIC-PHENIX
Hiroshi Nakagomi for the PHENIX collaboration
Univ. of Tsukuba
RIKEN

March 2nd 2016 WWND H.Nakagomi

1

Azimuthal anisotropic flow
Initial spatial anisotropy:ε2momentum anisotropy:v2

zxyAnisotropic particle production vn- Initial spatial condition is converted
to momentum anisotropy

Sensitive to-initial condition-viscosity
March 2nd 2016 WWND H.Nakagomi

PRL 106.192301

2Higher order flow harmonics
PRL 107. 252301

Event-by-event initial participant fluctuation can lead to triangularparticle production anisotropy v3.
v3 is expected to further constrains initial conditionand viscosity
March 2nd 2016 WWND H.Nakagomi

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Cu+Au collisions

Asymmetric initial condition provides- Different left/right pressure gradient, particle
production….
- Longitudinally, above characteristics could be
different in Au-going/Cu-goingvn measurements in CuAu collisions provide
additional insight into the mechanism
March 2nd 2016 WWND H.Nakagomi

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PHENIX detectors
2nd 3rd Participant Event Plane-Beam Beam counter(BBC)Spectator Plane-Shower Max Detector(SMD)
Charged particle Tracking-Drift Chamber(DC) (|η|<0.35)-Pad Chamber(PC) (|η|<0.35)-Electro magneticcalorimeter(EMC) (|η|<0.35)-Forward Vertex Detector(FVTX)(1<|η|<3)
Hadron identification-Time of flight(TOF) (|η|<0.35)
March 2nd 2016 WWND H.Nakagomi

5Charged hadron vn in CuAu
-pT dependence of v2, v3
System size dependence-pT and eta dependence of v1

March 2nd 2016 WWND H.Nakagomi

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System size dependence of v2
arxiv:1509.07784

v2 for different systems has similar centrality and pT dependence
v2 in CuAu is always between those in AuAu and CuCu
March 2nd 2016 WWND H.Nakagomi

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Scale v2 with ε2*Npart(1/3)
arxiv:1509.07784

PHENIX found empirical v2 scaling (PRC.92.034913)-v2 is scaled with ε2Npart(1/3)-Npart(1/3) is proportional to length scale
ε2Npart(1/3) scaling works well in CuAu!

March 2nd 2016 WWND H.Nakagomi

8System size dependence of v3
arxiv:1509.07784

v3 for different systems has weak centrality dependence
v3 in CuAu is always bigger than those in AuAu

March 2nd 2016 WWND H.Nakagomi

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Scale v3 with ε3*Npart(1/3)
arxiv:1509.07784

Empirical ε3Npart(1/3) scaling is performed-v3 is scaled with ε3Npart(1/3)-Npart(1/3) is proportional to length scale
ε3Npart(1/3) scaling works well in v3!
March 2nd 2016 WWND H.Nakagomi

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v1 measurement
v1 = <cos(φ-Ψ1)>

φΨ1The direction of Ψ1 is defined in Cu side spectator->v1>0 : more particle are emitted to Cu->v1<0 : more particle are emitted to Au-Measurement of v1 w.r.t Ψ1 using Au spectator and flipping
its sign
March 2nd 2016 WWND H.Nakagomi

11Charged hadron v1
arxiv:1509.07784

Sizable v1 at mid-rapidity is observed for 10-50%
High pt particle are emitted to Au side-Magnitude decreases from central to more peripheral events-In peripheral events, Left/Right path length becomes similar
March 2nd 2016 WWND H.Nakagomi

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v1

Rapidity dependence of v1
0.04

charged particles, p integrated, s NN=200GeVTBBC AuAu
BBC CuAu (SMD-Au-going)
BBC CuAu (SMD-Cu-going)
FVTX CuAu (SMD-Au-going)
FVTX CuAu (SMD-Cu-going)

0.02

0

Ψ pSP : Spectator Plane(projec0le)
Ψ tSP : Spectator Plane(target)ΨRP : Reac0on Plane

Ψ1Cu

Cu

v1>0? (η~0)
Cu going
Au going

Au
-0.02

E-by-E fluctuation lead toΨ1Au -4 -3 -2 -1 0 1 2 3 4“ΨS.P ≠ ΨS.P” -> “v1(ΨS.P) ≠ v1(ΨS.P)”-> v1 = v1(Traditional=η symmetric)
ηv1(fluctuation )+The difference of v1 is seen between two spectator planes.
- Same difference as seen in ALICE- Fluctuation ?
-0.04

30-40% Centrality



Traditional v1 in CuAu is positive at mid-rapidty ?
- more low pT particle emitted to Cu side ?
March 2nd 2016 WWND H.Nakagomi?

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Identified hadron vn

March 2nd 2016 WWND H.Nakagomi

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Identified particle v2 in CuAu
arxiv:1509.07784

Mass ordering at low pT for v2 for all centralities
Baryon and meson splitting at mid-pT is seen
March 2nd 2016 WWND H.Nakagomi

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Identified particle v3, v1 in CuAu
arxiv:1509.07784

PID v3-Same particle dependence of v3 is seen as seen in v2
PID v1-At low pt , mass ordering is not observed.
-Mass ordering is seen for v1 at 1<pT<2.5GeV-At high pt, baryon and meson splitting is not observed
March 2nd 2016 WWND H.Nakagomi

16Comparison to theory-Event-by-Event Hydro

March 2nd 2016 WWND H.Nakagomi

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MC-Glauber E-by-E hydro v2, v3
arxiv:1509.07784

For both centrality, both values of η/s agree with data
March 2nd 2016 WWND H.Nakagomi

18MC-Glauber E-by-E hydro v1(pt)arxiv:1509.07784

P. Bozek, Phys. Le.. B717 (2012) 287

In hydro calculation,-More low pT , particles are emitted to Cu side
-More high pT, particles are emitted to Au side
Theory calculation shows qualitative agreement.
March 2nd 2016 WWND H.Nakagomi

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v1

MC-Glauber E-by-E hydro v1(eta)charged particles, p integrated, s NN=200GeVT
BBC AuAu
BBC CuAu (SMD-Au-going)
BBC CuAu (SMD-Cu-going)
FVTX CuAu (SMD-Au-going)
FVTX CuAu (SMD-Cu-going)

0.04

0.02

0

Cu going
Au going

-0.02

-0.04

-4

30-40% Centrality-3-2-102314η

Comparison to theory for different centrality class
Hydro calculation doesn’t show a sign change of v1-In |eta|<4, sign of v1 is not changed
Magnitude of theory calculation is much smaller thanthose of experimental data
March 2nd 2016 WWND H.Nakagomi

20Summary
Charged Hadron vn-v2, v3 show same pT and centrality dependence as seen symmetriccollisions-Sizable v1 is measured at mid-rapidity-Fluctuation v1 is observed at RHIC
System size dependence of v2, v3- CuAu v2, v3 are scaled with 𝓔nNpart(1/3)
Identified Hadron vn-Mass ordering and Baryon and Meson splitting are seen in v2, v3- In mid-pT, Mass ordering is seen in v1,
Not observe Baryon and Meson splitting in v1
E-by-E hydro comparison-reproduces pt dependence of v2, v3-qualitatively reproduces pt dependence of v1,
but fails to explain η dependence of v1
March 2nd 2016 WWND H.Nakagomi

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Back Up

March 2nd 2016 WWND H.Nakagomi

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Charged pion v2, v3 in AuAu

March 2nd 2016 WWND H.Nakagomi

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Flow in symmetric collisions system

PRL 107,252301 

March 2nd 2016 WWND H.Nakagomi

H-31 Poster, Reynollds 24

Relative Heavy Ion Collider(RHIC)

PHENIX

March 2nd 2016 WWND H.Nakagomi

Species Energies
Au+Au 200, 130, 62.4GeV39, 27, 22.4GeV
19.6 14.6, 7.7GeV
Cu+Cu 200, 62.4, 22.4GeV
U+U
193GeVCu+Au 200GeV
3He+Au 200GeV
d+Au200GeV
p+Au200GeV
p+Al200GeV
p+p510, 500, 200GeV
62.4GeV25

Comparison to AMPT v2
arxiv:1509.07784

AMPT with 3mb reproduce v2-In 0-30%, up to 2GeV-In 30-60%, up to 1GeVMarch 2nd 2016 WWND H.Nakagomi

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Comparison to AMPT v3
arxiv:1509.07784

AMPT with 3mb reproduce v3-In 0-30%, up to 2GeV
March 2nd 2016 WWND H.Nakagomi

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v1v1

Rapidity dependence of v1
0.04

charged particles, p integrated, s NN=200GeVT
BBC AuAu
BBC CuAu (SMD-Au-going)
BBC CuAu (SMD-Cu-going)
FVTX CuAu (SMD-Au-going)
FVTX CuAu (SMD-Cu-going)

0.02

0

Ψ1Cu

charged particles, p integrated, s NN=200GeVT
BBC AuAu
BBC CuAu (SMD-Au-going)
BBC CuAu (SMD-Cu-going)
FVTX CuAu (SMD-Au-going)
FVTX CuAu (SMD-Cu-going)

Ψ1Cu

0.02
Cu going
Au going

-0.02

-0.04

0.04

0

Cu going
Au going-0.02

 

30-40% Centrality

Ψ1Au -4 -3 -2 -1 0

123

March 2nd 2016 WWND H.Nakagomi

4
η

-0.04

 

50-60% Centrality

Ψ1Au -4 -3 -2 -1 0

1234η

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<ε2>

March 2nd 2016 WWND H.Nakagomi

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<ε3>

March 2nd 2016 WWND H.Nakagomi

30Charged hadron v2
arxiv:1509.07784

Similar pT and centrality dependence of v2 as seenin symmetric collisions- Strong centrality dependence, magnitude increase
from central to peripheral
March 2nd 2016 WWND H.Nakagomi

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Charged hadron v3
arxiv:1509.07784

Similar pT and centrality dependence of v3 as seenin symmetric collisions- Weak centrality dependence, magnitude slightly increase
from central to peripheral
March 2nd 2016 WWND H.Nakagomi

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v1 Even, Odd Components in PbPb QM2011 ALICEü v1(even + odd) = v1(even) + v1(odd) is observed in PbPb 2.75[TeV]- v(even): v1(η) = v1(-η)- v1(odd) : v1(η) = -v1(-η)- The source of even component is expected from spectator fluctuation

March 2nd 2016 WWND H.Nakagomi

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P. Bozek, Phys. Le.. B717 (2012) 287

v1 evenv1 odd

March 2nd 2016 WWND H.Nakagomi

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No fluctuation
v1 = <cos(φ-Ψ)>SP fluctuation
ΔΨ’
ΔΨ’’

Weakly spectator fluctuation and &participant fluctuation are correlatedΔφv1 = <cos((φ+Δφ)-(Ψ+ΔΨ）)>= <cos(φ-Ψ)>+<cos(Δφ-ΔΨ)>= v1(traditional)+v1(SP fluctuation)

Δφ~ΔΨ’~ ΔΨ’:v1(SP fluctuation) >0 or <0Δφ≠ΔΨ≠ΔΨ’:no correlation v1(SP fluctuation)=0March 2nd 2016 WWND H.Nakagomi

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