1. Detail study of the medium created in Au+Au collisions with high p T probes by the PHENIX experiment at RHIC Takao Sakaguchi Brookhaven National Laboratory For the PHENIX Collaboration

2. Hard scattering as densimeter Parton may change its momentum in the medium. – Energy loss through Gluon radiation, etc.. Effect may be path-length and system dependent ~a densimeter~. Look at leading particles of jet as a measure of jet energy. 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 2 X.-N., Wang, PRC 58 (1998)2321 Energy loss =Yield suppress  0 without energy loss  0 with energy loss Yield [GeV -1 c] p T [GeV/c] PHENIX,  0 in Au+Au, PRL. 91, 072301 (2003)

3. Setup for measurement Event triggered by a coincidence of BBC South and BBC North. – Sitting in 3.1<|  |<3.9  0 and  measurement – EMCal(PbSc, PbGl): Energy measurement and identification of real photons. – Tracking(DC, PC): Veto to Charged particles. 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 3 View From Beam View From Side Results presented here are obtained from 0.813 nb -1 Au+Au 200GeV events recorded by PHENIX in 2007. 00  EMCal

4.  0 and  R AA 200GeV Au+Au collision system.  0 and  nicely agree. Very nice agreement between RHIC Year-2004 and 2007 results for  0. 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 4 PRC82, 011902(R) (2010) MinBias, Black:  0, Blue:  Black: Year-2004, Red: Year-2007 PRC87, 034911 (2013) MinBias Black- 2004 Red - 2007 0-10% 20-30% 40-50% 60-70%80-93%

5. Flavor similarity? Different quark flavor may give different interaction. – Mass ordering (dead-cone effect, etc.) At high p T (p T >5GeV/c), electrons from heavy quark (c,b) show similar R AA and R dA as  0 ’s from light quark (u,d) or gluons. 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 5 PHENIX, PRL. 109, 242301 (2012)

6. Path-length dependence of energy loss Comparison of R AA between data and models in in- and out-plane – Different path-length in in-plane (event plane direction) and out-plane. 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 6 PRC87, 034911 (2013)

7. Path-length dependence of energy loss Comparison of R AA between data and models in in- and out-plane – Different path-length in in-plane (event plane direction) and out-plane Data favor AdS/CFT-inspired model (very strong coupling) rather than pQCD-inspired (suggesting energy loss is L 3 dependent?). 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 7 PRC87, 034911 (2013)

8. Fractional momentum loss of partons Measured fractional momentum loss (  p T /p T ) instead of R AA – In A+A collisions  p T /p T =0.2 in 0-10% centrality, =0.02 in 70-80% centrality 2013-11-04 8 T. Sakaguchi, HP2013@Cape Town, South Africa  p T /p T PRC87, 034911 (2013) pTpT pTpT

9. Energy dependence of  p T /p T (I)  p T /p T decreases significantly going from 200 to 62, 39GeV. Significantly different  p T /p T even the R AA is similar. 2013-11-04 9 T. Sakaguchi, HP2013@Cape Town, South Africa R AA PRL109, 152301 (2012)

10. Energy dependence of  p T /p T (II)  p T /p T from 62GeV to 2.76TeV!: ~0.3 for LHC 2013-11-04 10 T. Sakaguchi, HP2013@Cape Town, South Africa PRL109, 152301 (2012) LHC RHIC PRC87, 034911 (2013)

11. Detail study of  p T /p T systematics Plotting against dN ch /d  (as a measure of energy density) – dN ch /d  are obtained in given centrality at given cms energy. –  p T /p T ‘s at p T =7GeV/c of p+p are plotted. 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 11

12. Detail study of  p T /p T systematics 200GeV trend points to ALICE 0-5% point? 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 12

13. Consistency with previous studies PHENIX studied fractional momentum loss in two publications – PRC76, 034904 (2007), PRL101, 232301 (2008) – Assuming the spectra shape is power-law with the power “n”, we can write: In this study, if we assume dN ch /d   N part, we can write the relationship as follows: 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 13

14. Consistency with previous studies PHENIX studied fractional momentum loss in two publications – PRC76, 034904 (2007), PRL101, 232301 (2008) – Assuming the spectra shape is power-law with the power “n”, we can write: In this study, if we assume dN ch /d   N part, we can write the relationship as follows: 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 14 PRL101, 232301 (2008)

15. v n of high p T probes 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 15

16. v 2 of high p T  0 and  v 2 of  0 and  are measured up to 14GeV/c. – They are very consistent as they are for R AA. We can reach to higher p T with  as accumulating more statistics. 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 16 PHENIX, arxiv:1309.4437

17. v 4 and v 2 of high p T  0 v 4 of  0 is measured up to 10GeV/c (using  2 event plane). v 4 /v 2 2 is computed. – Flatness of the ratio shows applicability of hydrodynamics..? 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 17 PHENIX, arxiv:1309.4437

18. Centrality dependence of v 4 /v 2 2 Charged hadron v 4 /v 2 2 compared with models – Ideal hydrodynamics only (I-Hd) – with eccentricity fluctuation (I-Hd +  -F) – with viscosity (I-Hd +  -F +  ) and Gaussian fluctuation (I-Hd + GF +  ) Different points correspond to six p T ranges in 0.5-3.6GeV/c 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 18 PHENIX, PRL105, 062301 (2010)

19. Hydro scaling extends to higher p T ? Plotted  0 v 4 /v 2 2 for p T >4GeV/c over charged hadron results. Hydro description still holds for this region? – Note possible effects from differential energy loss and/or jet bias – See prediction, e.g., Bravina et. al., PRC87, 034901(2013) 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 19 PHENIX, PRL105, 062301 (2010) - - - - - Points from  0 (p T >4GeV/c) Others from charged hadrons (p T <4GeV/c)

20. Summary  0 and  are measured in 200GeV Au+Au collisions. –  0 and  give very consistent results in R AA.  0 and HF electrons R AA and R dA have similar trend at high p T. – Similar degree of final state interaction for light and heavy quarks? Emission-angle dependent  0 yield favors AdS/CFT-inspired energy loss model. Centrality, system, and energy dependence of fractional momentum loss is studied. – A trend is seen from 200GeV Au+Au to 2.76TeV Pb+Pb Hydro description still holds for p T >4GeV/c? – From v 4 /v 2 2 measurement at high p T – Possible effects from differential energy loss and/or jet bias 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 20

21. Backup 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 21

22. How we measure  0,  ? Reconstruct hadrons via 2  invariant mass in EMCal (example is in Au+Au) Subtract Combinatorial background – Compute Mass using  s from different events. (mixed-event technique) 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 22 PRC87, 034911 (2013) PRC82, 011902(R) (2010)   00 

23. Detail study of  p T /p T systematics Plotting against dN ch /d  (as a measure of energy density) – dN ch /d  obtained in given centrality at given cms energy –  p T /p T ‘s at p T =7GeV/c of p+p are plotted 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 23

24. Detail study of  p T /p T systematics Re-plotted same data points in log-scale for dN ch /d  –  p T /p T ‘s at p T =7GeV/c of p+p are plotted 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 24

25.  0,  spectra in Au+Au 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 25 00  Spectra reached to ~20GeV/c for  0 and ~22GeV/c for 

26. Systematic errors Type A: point- by-point fluctuating errors Type B: p T - correlated errors Type C: overall normalization errors 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 26 sourcetype5GeV10GeV15GeV20GeV peak extractionB2222 acceptanceC2.5 PID efficiencyB788.59 energy scaleB7.5888 photon conversionC2222 cluster mergingB00818 total 11121522 sourcetype5GeV10GeV15GeV peak extractionB43.53 acceptanceC2.5 PID efficiencyB788.5 energy scaleB1112 photon conversionC222 total 1215  0 systematic errors  systematic errors

27. v 4 and v 2 of high p T  0 v 4 of  0 is measured up to 10GeV/c (using  2 event plane) 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 27 PHENIX, arxiv:1309.4437  0 v 4  0 v 2

28. d+Au and Au+Au system similarity? Au+Au 60-92% and d+Au 0- 20% have similar N part, N coll Ratios of all ID’ed hadron spectra are on the same curve Common production mechanism? If all CNM scales with N part, ratios may mean E loss in the medium in peripheral Au+Au Low p T increase may rise from rapidity shift in d+Au 2013-11-04T. Sakaguchi, HP2013@Cape Town, South Africa 28 arXiv:1304.3410