Azimuthal anisotropy measurement of neutral pion and direct photon
in sNN=200GeV Au+Au collisions at RHIC-PHENIX
TAC seminar
11/25/2008
Kentaro MIKIKentaro MIKIUniv. of TsukubaUniv. of Tsukuba
mail to: [email protected] to: [email protected]
11 / 25 / 2008 Kentaro Miki 2
1. Introduction
1. Introduction
2. Physics Motivation
3. Experiment
4. Data Reduction
5. Data Analysis
6. Result / Discussion
7. Conclusion / Summary
- Quark Gluon Plasma- Electro Magnetic Particle - Physic result at RHIC
11 / 25 / 2008 Kentaro Miki 3
1-1. Quark Gluon Plasma
Quark Gluon Plasma -> The quark and the gluon move freely in a large volume. -> QGP formed under high temperature and energy density.
Is there an end in the size of the matter?
Heavy Ion Collision Experiment -> High temperature and high density necessary for generating QGP is produced by the high energy heavy ion collisions.
11 / 25 / 2008 Kentaro Miki 4
1-2. Heavy Ion Collision Experiment
In order to provide the QGP state on the ground, Au nucleus is collidedat sNN = 200 GeV by the RelativisticHeavy Ion Collider at BNL.
Critical temperature / energy density by Lattice QCD
Tc ~ 170 MeVc ~ 1.2 GeV/fm3
11 / 25 / 2008 Kentaro Miki 5
1-3. Electro Magnetic Particles
Electro magnetic particles are the powerful probes to the studyproperty of QGP since they do not interaction strongly with any other particles and thus can carry out information on the states where they are emitted.
Photons are emitted from all stage of collisions.
Cartoon from Dinesh K. Srivastava, Quark Matter 2008
11 / 25 / 2008 Kentaro Miki 6
1-4. Production Process
Annihilation + Compton
fragment
Direct photon production process in p+p collisions
process1 (Annihilation + Compton Scattering)
process2 (Fragmentation)
Isolated direct photon cut : 0.1*E > Econe(R=0.5)Isolation cut can reduce the bremmstrahlung photons
parton distribution function (PDF) process1 process2 fragmentation function (PDF)
11 / 25 / 2008 Kentaro Miki 7
1-5. Ratio of Photons
QGP-Thermal Jet-photon
NLO-pQCD
All
High pT direct photons are well described byNLO-pQCD calculation.
Phys. Rev., C69:014903(2004)
thermal window -> 1~3 GeV/c prompt photon window -> 6~ GeV/c
High pT direct photons are produced in the initial stage.Thermal radiation are emitted in the low pT region.
11 / 25 / 2008 Kentaro Miki 8
1-6. High pT Direct Photon Yield
NLO-pQCD calculation well described the photon data of p+p collisionsin the world experiment.
Blue line: Ncoll scaled p+p cross section
High pT Photon yield in Au+Au is also well explained by NLO-pQCD.
11 / 25 / 2008 Kentaro Miki 9
1-7. Nuclear Modification Factor
Non jet quench on the Direct photon
Probe of isospin effect in high pT ?
ppcoll
AuAuAA YieldN
YieldR
pT scaled by 62.4/200
(xT scaling inspired) -> difference of quark charge between neutrons and photons-> yield of photons from p+p, p+n and n+n should have different value.-> The difference of photon yield from Au+Au and p+p would be appeared in RAA of direct photon.
11 / 25 / 2008 Kentaro Miki 10
1-8. Direct Photon History
log t
pT
1 10 107
(GeV)
hadrondecays
hadron gas sQGP
hard scatter
jet Brems.jet-thermal
jet fragmentation
Cartoon from G. David, Hard Probe 2006
Photons emitted from all stage in the history of hot dense medium.
How distinguish one photon from all emissions?
11 / 25 / 2008 Kentaro Miki 11
2. Physics Motivation
1. Introduction
2. Physics Motivation
3. Experiment
4. Data Reduction
5. Data Analysis
6. Result / Discussion
7. Conclusion / Summary
- Azimuthal Anisotropy- Prediction of Photon v2
- My Activity
11 / 25 / 2008 Kentaro Miki 12
2-1. Azimuthal Anisotropy
: azimuthal angle of particles : azimuthal angle of reaction plane
-Elliptic flow (v2) is defined by the 2nd coefficient of Fourier expansion
The collision participation part in the early stage has spatial anisotropy. Pressure gradient is the largest in the shortest direction of the ellipsoid. Emitted particles reflect initial spatial anisotropy.
11 / 25 / 2008 Kentaro Miki 13
2-2. Emission Processes
Photons are emitted from all stage of heavy ion collisions!
Hard Scattered
sQGP Thermal
Jet Fragmentation
Hadron Decay
Jet Bremmstrahlung
11 / 25 / 2008 Kentaro Miki 14
2-3. Prediction
Hard Scatter
Jet Brems.
Jet Fragment
QGP
v2 = 0
v2 < 0
v2 > 0
v2 ≥ 0
annihilationcompton scattering
Bremsstrahlung (energy loss)
v2 > 0
v2 < 0
Photon emission from jet
Turbide, Gale, arXiv:0712.0732
The sign of v2 depending on the production processes of photons.
v2 is a powerful tool to explore the source of direct photons.
11 / 25 / 2008 Kentaro Miki 15
2-4. My Activity
2006
2007
2008
01.08 RHIC-AGS meeting
03.27 JPA -spring-
BNL
09.21 JPA -fall-
11.16-20 QM2006 in Shanghai
11.24 International workshop in Xi’an
BNL BNL
BNL
04.01 Junior Research Associate
02.08 QM2008 in India
11.01 start up RHIC Run8
BNL
Centrality calibration for Run7
preliminary request for pi0 v2 in Run7
preliminary request for direct photon v2 in Run4
TOF calibration for Run6
11 / 25 / 2008 Kentaro Miki 16
3. Experiment
1. Introduction
2. Physics Motivation
3. Experiment
4. Data Reduction
5. Data Analysis
6. Result / Discussion
7. Conclusion / Summary
- Relativistic Heavy Ion Collider- the Pioneering High Energy Nuclear Interaction eXperiment
11 / 25 / 2008 Kentaro Miki 17
3-1. RHICAccelerators Tandem Van de Graaff Linear Accelerator Booster Synchrotron Alternating Gradient Synchrotron Relativistic Heavy Ion Collider
Experiments PHENIX, STAR, BRAHMS, PHOBOS
11 / 25 / 2008 Kentaro Miki 18
3-2. PHENIX Detectors
lead scintillator (PbSc)・ energy resolution 2.1 8.1 %/ E1/2 [GeV]
lead glass (PbGl)・ energy resolution 0.76 5.95 %/ E1/2 [GeV]
Reaction Plane Detector 1.0 < || < 2.8 16 sectors in each side
Beam-Beam counter event trigger reaction plane determination
11 / 25 / 2008 Kentaro Miki 19
4. Data Reduction
1. Introduction
2. Physics Motivation
3. Experiment
4. Data Reduction
5. Data Analysis
6. Result / Discussion
7. Conclusion / Summary
- Photon Identify- Calibrations
11 / 25 / 2008 Kentaro Miki 20
4-1. Photon Identify
1. Cluster
2. Peak area
3. EMCal shower
11 / 25 / 2008 Kentaro Miki 21
4-2. Calibration ~Centrality~
The centrality is determined by the correlation of BBC charge sum and ZDC energy in PHENIX. The boundaries of centralities are calibratedto make flat the centrality distribution.
<Clock method in Run4>
<BBC charge sum method in Run7>
11 / 25 / 2008 Kentaro Miki 22
4-3. Calibration ~Reaction Plane~
<Reaction Plane Resolution>
11 / 25 / 2008 Kentaro Miki 23
5. Data Analysis
1. Introduction
2. Physics Motivation
3. Experiment
4. Data Reduction
5. Data Analysis
6. Result / Discussion
7. Conclusion / Summary
- Inclusive Photon- 0
- Hadron Decay by Simulation- Direct Photon
11 / 25 / 2008 Kentaro Miki 24
5-1. Data analysis
Direct hadron decay
Inclusive photon
0 ’
2nd harmonic amplitude : v2
11 / 25 / 2008 Kentaro Miki 25
5-2. Inclusive photon
Event / Cluster cut : BBC vertex < 30 cm ZDCNS > 1 Centrality defined by BBC only Reaction plane defined by RxNP emc Cluster energy > 0.2 GeV pc3 rejection cut > 6.5 cm
Centrality : 0-92% (10% step) pT range : 1.0 - 16.0 [GeV/c]Data Set : Au+Au 200 GeV Run4 (~800M events) Run7 (~4.0G events)
11 / 25 / 2008 Kentaro Miki 26
5-3. Inclusive photon v2 (Run7)
Fitting Function
11 / 25 / 2008 Kentaro Miki 27
5-4. Invariant mass distribution of 0
Invariant mass distribution of 2
dN / dphi distribution of pi0
Basically, same cut with inclusive photon analysis. Combinatrial back ground isestimated by event mix distribution.
11 / 25 / 2008 Kentaro Miki 28
5-5. 0 raw yield
Filled circle : 0 raw yieldOpened circle : 0 yield at Run4 PHENIX preliminary
Au+Au 200 GeV
11 / 25 / 2008 Kentaro Miki 29
5-6. Hadron decay contamination
Since components other than 0 cannot be measure directly,the hadron decay contamination is estimated by using Monte-Carlo.
11 / 25 / 2008 Kentaro Miki 30
5-7. Hadron decay photon v2
Hadron decay photon v2 is estimated by Exodus using mT scaled 0 v2.
point-to-point fitting above 5 GeV
mT scaled v2 for Exodus input
up/down line : sys. error from 0 statistical error
Decay photon v2 from each parent particles.
11 / 25 / 2008 Kentaro Miki 31
5-8. Cocktail
above 3GeV, 0 77.6 % 19.0 % 3.7 % 0.5 % ’ 2.0 %
Parent spectra from Exodus output.Red point is measured data of 0 (PPG080).0 output is normalized by data.other hadrons are normalized by 0
and their decay ratio.
Cocktailed the decay photons v2
according to contamination ratio.
11 / 25 / 2008 Kentaro Miki 32
5-9. Direct photon v2
1
* _2
.2.
2
R
vvRv
photonBGphotonincphotondir
photonBG
photoninc
N
NR
_
.
11 / 25 / 2008 Kentaro Miki 33
6. Result / Discussion
1. Introduction
2. Physics Motivation
3. Experiment
4. Data Reduction
5. Data Analysis
6. Result / Discussion
7. Conclusion / Summary
11 / 25 / 2008 Kentaro Miki 34
6-1. Run4 Result
Inclusive / Hadron Decay / Direct photon v2 in Run4 200GeV Au+Au
- Photon v2 is measured up to 10GeV/c.- Consistent with zero.
11 / 25 / 2008 Kentaro Miki 35
6-2. Run7 Inclusive Photon
Inclusive Photon v2 in Run7 by using RxNP
- Measured 10% and 20% steps of centrality.- Extended up to 16.0 GeV/c
11 / 25 / 2008 Kentaro Miki 36
6-3. Run7 0 v2
0 v2 is estimated by using RxNP in Run7 up to 16.0 [GeV/c].
- Measured 10% and 20% steps of centrality.- Extended up to 16.0 GeV/c
11 / 25 / 2008 Kentaro Miki 37
6-4. Comparison with Hadrons
The 0 v2 compared with charged hadron v2.
- 0 v2 is good agreement with pion v2 (Run4).- There is un-consistency between the result from RxNP and BBC above 4GeV/c.
11 / 25 / 2008 Kentaro Miki 38
6-5. Hadron Decay Photon v2
Inclusive Photon v2 and Hadron Decay Photon v2 in Run7 by using RxNP
- Significant different is appeared between Inclusive and hadron decay in high pT.- The systematic error on hadron decay is propagated from statistical and systematic error of 0.
11 / 25 / 2008 Kentaro Miki 39
6-6. Direct Photon v2
Direct Photon v2 in Run7 by using RxNP - extended up to 16GeV/c- run4 double ratio is used- Non-Zero v2 about 3GeV ?- Centrality dependence
annihilationcompton scattering
Bremsstrahlung (energy loss)
v2 > 0
v2 < 0
11 / 25 / 2008 Kentaro Miki 40
6-7. Comparison with the result by BBC.
Reaction Plane angle is defined by RxNP
Reaction Plane angle is defined by BBC
Central Arm || < 0.35BBC 3.0 < |eta| < 3.9 RxNP 1.0 < |eta| < 2.8
11 / 25 / 2008 Kentaro Miki 41
6-8. Comparison with Theoretical Prediction
RxNP
BBC
arXiv:0712.0732v2
11 / 25 / 2008 Kentaro Miki 42
6-9. Comparison with RAA
In the 2~4 GeV/c region, 1. Enhancement of direct photon in Au+Au 2. Direct photon v2 might be non-zero
=> There is other components ??
11 / 25 / 2008 Kentaro Miki 43
6-10. Additional Analysis
> Direct photon v2 in Run7 still has large error bar…
Estimation of thermal photon from virtual gamma analysis
How to improve the Direct photon v2 resultin low pT region?
11 / 25 / 2008 Kentaro Miki 44
6-11. Virtual Photon Analysis
÷
÷÷
0-3
0
90-1
40
140-2
00
200-3
00
Rdata
32
222
2
2
2
2
112
14
13
21)
M
m()m(F
m)
m
m(
m
m
dm
dN
Nee
eeeeee
e
ee
e
ee
ee
Kroll-Wada Formula
11 / 25 / 2008 Kentaro Miki 45
6-12. Thermal Photon Spectra
(inclusive) = (decay) + (direct)
Double ratio: (incl/0)measured / (decay/ 0)background = incl/ decay =1+ direct/ decay
Compare to NLO pQCD (p+p consistent with pQCD)Compare to thermal model D. d’Enterria, D. Peressounko (nucl-th/0503054)2+1 hydroT0
ave=360 MeV (T0max=570 MeV)
0=0.15 fm/cData consistent with thermal + pQCD
11 / 25 / 2008 Kentaro Miki 46
6-13. Thermal Photon v2 ??
RxNP
- Improved below 3GeV/c- Ordinary method should be used above 4GeV/c
RxNP BBC
11 / 25 / 2008 Kentaro Miki 47
6-14. Thermal Photon v2
Comparison the final result with direct photon prediction.
- Photon v2 is larger than theoretical curve.- Need to check thecalculation model.- Need to check withthe discussion of hadron analysis.
11 / 25 / 2008 Kentaro Miki 48
7-1. Conclusion
- 0 and inclusive photon v2 is very effective probe to study the high pT region.
- Direct photon seems to have non-zero v2 above 3GeV/c.
- The influence of jet (or jet-suppression) is appeared even direct photon.
- Virtual photon analysis is effective in low pT region.
- Thermal photon v2 is larger than theoretical prediction curve described in arXiv:0712.0732v2.
- Need to more physics study with charged hadron analysis or several models.
11 / 25 / 2008 Kentaro Miki 49
7-2. Summary
- Estimated inclusive / 0 / hadron decay photon v2 at 10% steps and 20% steps up to 60% and minimum bias.- direct photon v2 measured using RxNP or BBC. - estimated the low pT direct photon v2 by using the double ratio which is calculated in the thermal photon analysis.
- Extended pT range up to 16 GeV/c- Improved v2 accuracy below 3 GeV/c
Tasks…
- Applying new energy calibration.- Systematic error study of remaining hadrons on the inclusive photon - Comparison with charged hadron data and several models.
11 / 25 / 2008 Kentaro Miki 50
Ex
Back up
11 / 25 / 2008 Kentaro Miki 51
Ex. Systematical uncertainty
Systematical error on the inclusive photon v2 is estimated from 4 sources.
1. PID photon identification cut ON/OFF
2. Method dN / dphi vs average cosine <2*cos(2d)>
3. Reaction Plane Estimated by BBC in Run2
4. Hadrons Remaining hadrons contamination after photon cut
11 / 25 / 2008 Kentaro Miki 52
Ex. Double Ratio
11 / 25 / 2008 Kentaro Miki 53
Q=pT/sqrt(2) for prompt calculations, Turbide et al. (see also Arleo, JHEP 0609, 015 (2006), Liu & Werner, hep-ph/0712.3619 and Liu & Fries, nucl-th/0801.0453 . ).
