Azimuthal anisotropy measurement of neutral pion and direct

Azimuthal anisotropy measurement of neutral pion and direct photon in s. NN=200 Ge. V Au+Au collisions at RHIC-PHENIX TAC seminar Kentaro Miki 11 / 25 / 2008 Kentaro MIKI Univ. of Tsukuba mail to: kentaro@rcf 2. rhic. bnl. gov 11/25/2008

1. Introduction 2. Physics Motivation - Quark Gluon Plasma - Electro Magnetic Particle - Physic result at RHIC 3. Experiment 4. Data Reduction 5. Data Analysis 6. Result / Discussion 7. Conclusion / Summary 11 / 25 / 2008 Kentaro Miki 2

1 -1. Quark Gluon Plasma Is there an end in the size of the matter? Quark Gluon Plasma -> The quark and the gluon move freely in a large volume. -> QGP formed under high temperature and energy density. 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 3

1 -2. Heavy Ion Collision Experiment In order to provide the QGP state on the ground, Au nucleus is collided at s. NN = 200 Ge. V by the Relativistic Heavy Ion Collider at BNL. Critical temperature / energy density by Lattice QCD Tc ~ 170 Me. V c ~ 1. 2 Ge. V/fm 3 11 / 25 / 2008 Kentaro Miki 4

1 -3. Electro Magnetic Particles Electro magnetic particles are the powerful probes to the study property 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 5

1 -4. Production Process Direct photon production process in p+p collisions process 1 (Annihilation + Compton Scattering) process 2 (Fragmentation) parton distribution function (PDF) process 1 process 2 fragmentation function (PDF) Annihilation + Compton fragment Isolated direct photon cut : 0. 1*E > Econe(R=0. 5) Isolation cut can reduce the bremmstrahlung photons 11 / 25 / 2008 Kentaro Miki 6

1 -5. Ratio of Photons High p. T direct photons are produced in the initial stage. Thermal radiation are emitted in the low p. T region. All NLO-p. QCD thermal window -> 1~3 Ge. V/c prompt photon window -> 6~ Ge. V/c Phys. Rev. , C 69: 014903(2004) 11 / 25 / 2008 QGP-Thermal Jet-photon High p. T direct photons are well described by NLO-p. QCD calculation. Kentaro Miki 7

1 -6. High p. T Direct Photon Yield NLO-p. QCD calculation well described the photon data of p+p collisions in the world experiment. Blue line: Ncoll scaled p+p cross section High p. T Photon yield in Au+Au is also well explained by NLO-p. QCD. 11 / 25 / 2008 Kentaro Miki 8

1 -7. Nuclear Modification Factor Non jet quench on the Direct photon Probe of isospin effect in high p. T ? -> 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 p. T scaled by 62. 4/200 (x. T scaling inspired) 9

1 -8. Direct Photon History Photons emitted from all stage in the history of hot dense medium. hard scatter p. T (Ge. V) How distinguish one photon from all emissions? jet Brems. jet-thermal jet fragmentation s. QGP hadron gas 1 10 hadron decays 107 log t Cartoon from G. David, Hard Probe 2006 11 / 25 / 2008 Kentaro Miki 10

2. Physics Motivation 1. Introduction 2. Physics Motivation 3. Experiment - Azimuthal Anisotropy - Prediction of Photon v 2 - My Activity 4. Data Reduction 5. Data Analysis 6. Result / Discussion 7. Conclusion / Summary 11 / 25 / 2008 Kentaro Miki 11

2 -1. Azimuthal Anisotropy 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. -Elliptic flow (v 2) is defined by the 2 nd coefficient of Fourier expansion : azimuthal angle of particles : azimuthal angle of reaction plane 11 / 25 / 2008 Kentaro Miki 12

2 -2. Emission Processes Photons are emitted from all stage of heavy ion collisions! s. QGP Thermal Jet Fragmentation Hadron Decay Hard Scattered Jet Bremmstrahlung 11 / 25 / 2008 Kentaro Miki 13

2 -3. Prediction Hard Scatter v 2 = 0 Jet Brems. v 2 < 0 Jet Fragment v 2 > 0 QGP The sign of v 2 depending on the production processes of photons. v 2 is a powerful tool to explore the source of direct photons. v 2 ≥ 0 Photon emission from jet annihilation compton scattering v 2 > 0 Bremsstrahlung (energy loss) v 2 < 0 Turbide, Gale, ar. Xiv: 0712. 0732 11 / 25 / 2008 Kentaro Miki 14

2 -4. My Activity 2006 01. 08 RHIC-AGS meeting BNL 09. 21 JPA -fall- TOF calibration for Run 6 BNL 03. 27 JPA -springpreliminary request for direct photon v 2 in Run 4 11. 16 -20 QM 2006 in Shanghai 11. 24 International workshop in Xi’an 2007 04. 01 Junior Research Associate preliminary request for pi 0 v 2 in Run 7 BNL Centrality calibration for Run 7 11. 01 start up RHIC Run 8 2008 02. 08 QM 2008 in India BNL 11 / 25 / 2008 Kentaro Miki 15

3. Experiment 1. Introduction 2. Physics Motivation 3. Experiment 4. Data Reduction - Relativistic Heavy Ion Collider - the Pioneering High Energy Nuclear Interaction e. Xperiment 5. Data Analysis 6. Result / Discussion 7. Conclusion / Summary 11 / 25 / 2008 Kentaro Miki 16

3 -1. RHIC Accelerators 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 17

3 -2. PHENIX Detectors Reaction Plane Detector 1. 0 < | | < 2. 8 16 sectors in each side Beam-Beam counter event trigger reaction plane determination lead glass (Pb. Gl) ・energy resolution 0. 76 5. 95 %/ E 1/2 [Ge. V] lead scintillator (Pb. Sc) ・energy resolution 2. 1 8. 1 %/ E 1/2 [Ge. V] 11 / 25 / 2008 Kentaro Miki 18

4. Data Reduction 1. Introduction 2. Physics Motivation 3. Experiment 4. Data Reduction - Photon Identify - Calibrations 5. Data Analysis 6. Result / Discussion 7. Conclusion / Summary 11 / 25 / 2008 Kentaro Miki 19

4 -1. Photon Identify 1. Cluster 2. Peak area 3. EMCal shower 11 / 25 / 2008 Kentaro Miki 20

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 calibrated to make flat the centrality distribution. <BBC charge sum method in Run 7> <Clock method in Run 4> 11 / 25 / 2008 Kentaro Miki 21

4 -3. Calibration ~Reaction Plane~ <Reaction Plane Resolution> 11 / 25 / 2008 Kentaro Miki 22

5. Data Analysis 1. Introduction 2. Physics Motivation 3. Experiment 4. Data Reduction 5. Data Analysis 6. Result / Discussion - Inclusive Photon - 0 - Hadron Decay by Simulation - Direct Photon 7. Conclusion / Summary 11 / 25 / 2008 Kentaro Miki 23

5 -1. Data analysis Inclusive photon Direct hadron decay 0 ’ 2 nd harmonic amplitude : v 2 11 / 25 / 2008 Kentaro Miki 24

5 -2. Inclusive photon Centrality : 0 -92% (10% step) p. T range : 1. 0 - 16. 0 [Ge. V/c] Data Set : Au+Au 200 Ge. V Run 4 (~800 M events) Run 7 (~4. 0 G events) Event / Cluster cut : BBC vertex < 30 cm ZDCNS > 1 Centrality defined by BBC only Reaction plane defined by Rx. NP emc Cluster energy > 0. 2 Ge. V pc 3 rejection cut > 6. 5 cm 11 / 25 / 2008 Kentaro Miki 25

5 -3. Inclusive photon v 2 (Run 7) Fitting Function 11 / 25 / 2008 Kentaro Miki 26

5 -4. Invariant mass distribution of 0 Basically, same cut with inclusive photon analysis. Combinatrial back ground is estimated by event mix distribution. Invariant mass distribution of 2 d. N / dphi distribution of pi 0 11 / 25 / 2008 Kentaro Miki 27

5 -5. 0 raw yield Au+Au 200 Ge. V Filled circle : 0 raw yield Opened circle : 0 yield at Run 4 PHENIX preliminary 11 / 25 / 2008 Kentaro Miki 28

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 29

5 -7. Hadron decay photon v 2 is estimated by Exodus using m. T scaled 0 v 2. point-to-point fitting above 5 Ge. V m. T scaled v 2 for Exodus input Decay photon v 2 from each parent particles. up/down line : sys. error from 0 statistical error 11 / 25 / 2008 Kentaro Miki 30

5 -8. Cocktail above 3 Ge. V, 0 77. 6 % 19. 0 % 3. 7 % 0. 5 % ’ 2. 0 % Parent spectra from Exodus output. Red point is measured data of 0 (PPG 080). 0 output is normalized by data. other hadrons are normalized by 0 and their decay ratio. Cocktailed the decay photons v 2 according to contamination ratio. 11 / 25 / 2008 Kentaro Miki 31

5 -9. Direct photon v 2 11 / 25 / 2008 Kentaro Miki 32

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 33

6 -1. Run 4 Result Inclusive / Hadron Decay / Direct photon v 2 in Run 4 200 Ge. V Au+Au - Photon v 2 is measured up to 10 Ge. V/c. - Consistent with zero. 11 / 25 / 2008 Kentaro Miki 34

6 -2. Run 7 Inclusive Photon v 2 in Run 7 by using Rx. NP - Measured 10% and 20% steps of centrality. - Extended up to 16. 0 Ge. V/c 11 / 25 / 2008 Kentaro Miki 35

6 -3. Run 7 0 v 2 is estimated by using Rx. NP in Run 7 up to 16. 0 [Ge. V/c]. - Measured 10% and 20% steps of centrality. - Extended up to 16. 0 Ge. V/c 11 / 25 / 2008 Kentaro Miki 36

6 -4. Comparison with Hadrons The 0 v 2 compared with charged hadron v 2. - 0 v 2 is good agreement with pion v 2 (Run 4). - There is un-consistency between the result from Rx. NP and BBC above 4 Ge. V/c. 11 / 25 / 2008 Kentaro Miki 37

6 -5. Hadron Decay Photon v 2 Inclusive Photon v 2 and Hadron Decay Photon v 2 in Run 7 by using Rx. NP - Significant different is appeared between Inclusive and hadron decay in high p. T. - The systematic error on hadron decay is propagated from statistical and systematic error of 0. 11 / 25 / 2008 Kentaro Miki 38

6 -6. Direct Photon v 2 in Run 7 by using Rx. NP - extended up to 16 Ge. V/c - run 4 double ratio is used - Non-Zero v 2 about 3 Ge. V ? - Centrality dependence Bremsstrahlung (energy loss) annihilation compton scattering v 2 > 0 v 2 < 0 11 / 25 / 2008 Kentaro Miki 39

6 -7. Comparison with the result by BBC. Reaction Plane angle is defined by Rx. NP Reaction Plane angle is defined by BBC Central Arm | | < 0. 35 BBC 3. 0 < |eta| < 3. 9 Rx. NP 1. 0 < |eta| < 2. 8 11 / 25 / 2008 Kentaro Miki 40

6 -8. Comparison with Theoretical Prediction Rx. NP BBC ar. Xiv: 0712. 0732 v 2 11 / 25 / 2008 Kentaro Miki 41

6 -9. Comparison with RAA In the 2~4 Ge. V/c region, 1. Enhancement of direct photon in Au+Au 2. Direct photon v 2 might be non-zero => There is other components ? ? 11 / 25 / 2008 Kentaro Miki 42

6 -10. Additional Analysis How to improve the Direct photon v 2 result in low p. T region? > Direct photon v 2 in Run 7 still has large error bar… Estimation of thermal photon from virtual gamma analysis 11 / 25 / 2008 Kentaro Miki 43

6 -11. Virtual Photon Analysis 200 -300 0 -30 140 -200 90 -140 Kroll-Wada Formula Rdata ÷ ÷ ÷ 11 / 25 / 2008 Kentaro Miki 44

6 -12. Thermal Photon Spectra (inclusive) = (decay) + (direct) Double ratio: ( incl/ 0)measured / ( decay/ 0)background = incl/ decay =1+ direct/ decay Compare to NLO p. QCD (p+p consistent with p. QCD) Compare to thermal model D. d’Enterria, D. Peressounko (nucl-th/0503054) 2+1 hydro T 0 ave=360 Me. V (T 0 max=570 Me. V) 0=0. 15 fm/c Data consistent with thermal + p. QCD 11 / 25 / 2008 Kentaro Miki 45

6 -13. Thermal Photon v 2 ? ? - Improved below 3 Ge. V/c - Ordinary method should be used above 4 Ge. V/c Rx. NP 11 / 25 / 2008 BBC Kentaro Miki 46

6 -14. Thermal Photon v 2 Comparison the final result with direct photon prediction. - Photon v 2 is larger than theoretical curve. - Need to check the calculation model. - Need to check with the discussion of hadron analysis. 11 / 25 / 2008 Kentaro Miki 47

7 -1. Conclusion - 0 and inclusive photon v 2 is very effective probe to study the high p. T region. - Direct photon seems to have non-zero v 2 above 3 Ge. V/c. - The influence of jet (or jet-suppression) is appeared even direct photon. - Virtual photon analysis is effective in low p. T region. - Thermal photon v 2 is larger than theoretical prediction curve described in ar. Xiv: 0712. 0732 v 2. - Need to more physics study with charged hadron analysis or several models. 11 / 25 / 2008 Kentaro Miki 48

7 -2. Summary - Estimated inclusive / 0 / hadron decay photon v 2 at 10% steps and 20% steps up to 60% and minimum bias. - direct photon v 2 measured using Rx. NP or BBC. - estimated the low p. T direct photon v 2 by using the double ratio which is calculated in thermal photon analysis. - Extended p. T range up to 16 Ge. V/c - Improved v 2 accuracy below 3 Ge. V/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 49

Ex Back up 11 / 25 / 2008 Kentaro Miki 50

Ex. Systematical uncertainty Systematical error on the inclusive photon v 2 is estimated from 4 sources. 1. PID photon identification cut ON/OFF 2. Method d. N / dphi vs average cosine <2*cos(2 d )> 3. Reaction Plane Estimated by BBC in Run 2 4. Hadrons Remaining hadrons contamination after photon cut 11 / 25 / 2008 Kentaro Miki 51

Ex. Double Ratio 11 / 25 / 2008 Kentaro Miki 52

Q=p. T/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. ). 11 / 25 / 2008 Kentaro Miki 53