1. Jet/Photon/Hadron Correlations at RHIC-PHENIX
Kenta Shigaki (Hiroshima University )
for the X Collaboration
International Workshop on High pT Physics 2012
October 22, 2012
Central China Normal University, Wuhan, China

2. HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki
presentation outline
direct g as established ultimate trigger
direct g–hadron correlation
quark energy loss, fragmentation, (re-)distribution
enhancement/suppression w.r.t. “initial” quark energy
away (jet) side angular shape
reconstructed jet
sPHENIX
summary and concluding remarks
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

3. direct g : ultimate trigger particle
non-modified reference trigger
cf. both sides modified in jet–jet, jet–h, h–h
no surface bias
trigger g energy  partner energy in leading order
dominantly tagging (u-, d-)quark-jets
though with additional electro-magnetic a
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

4. direct g : solid p+p baseline
higher statistics dataset
pT reach extended by ~ 2
precision improved by > 2
more precise isolated fraction
90% isolation in R < 0.5
possibility to use isolated component
PHENIX, arXiv: ,
submitted to PRD
isolated / all photon
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

5. direct g : Au+Au analysis finalized
2004 Au+Au data analysis finalized
spectra published with better precision
systematics (e.g. p0 merging) studied in detail
PHENIX, PRL 109, (2012)
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

6. direct g : established as reference
absence of suppression re-confirmed
models resulting in suppression looking no longer viable
PRL 109,
gdir p0
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

7. direct g–hadron correlation
function of momentum fraction w.r.t. direct g
z  pT (hadron) / pT (direct g)
x  - log (z)
decay g–hadron correlation statistically subtracted
direct/inclusive g ratio from new single g analysis
decay g–hadron ~ p0–hadron correlation
flow modulation included
recent statistical improvements
combined 2007 and 2010 data sets
wider 0–40% centrality bin
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

8. quark energy loss and re-distribution
high z (low x) suppressed; low z (high x) enhanced
improved statistics
“lost” jet also accounted for
cf. LHC non effect at z = 1
only within identified jets
0.7
0.9
0.5
0.4
0.3
0.2
0.1
0.05
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

9. closer look at energy re-distribution
wider away (jet) side enhancement at lower z
low z
high z
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

10. another view: angular shape analysis
evolution with away (jet) side angle range
rise from high to low z in all integration ranges
less low z enhancement in jet “core” region
little angle range dependence at high z
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

11. HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki
not just vn effect
flow effects as background correlations
v3, v4 heavily affecting away side structure and residual
broadening not explained just with v3, v4, …
tested with conservatively large v3, v4 at high pT
vn effects mostly canceled in decay g–hadron subtraction
higher pT
lower pT
v2 only
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

12. jet reconstruction in PHENIX
Gaussian filter:
developed for heavy ion collision backgrounds
seedless, cone-like algorythm
optimized to find energetic jet core
jet axis stabilized against background particles
p+p measurement matches well with pQCD
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

13. HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki
powerfulness of jet
extended kinematic reach
surprising centrality dependence in d+Au
cf. initial state effects in direct g interesting
different systematics between jet and hadron (p0)
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

14. jet and hadron comparison (in d+Au)
empirical pT scaling factor <z> = 0.7
fragmentation not obviously modified
ref. talk by D.V.Perepelitsa
implying fragments as in vacuum after energy loss
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

15. toward complete scenario
quark energy loss
suppression at high z (low x)
enhancement at low z (high x)
un-(or-little-)modified fragmentation (tbc in Au+Au)
consistent RdAu for jets and hadrons
(thermal-like) energy re-distribution
wider away (jet) side enhancement in lower z (high x) x
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

16. HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki
outlook: sPHENIX
high rate capability and large acceptance
106 jets per year above 30 GeV/c
104 direct g per year above 20 GeV/c
differential measurements (v2, v3, …)
controlled geometry measurements (A+B, U+U)
precise control measurements (p+p, d+Au)
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

17. direct g at RHIC/sPHENIX
nice overlap with jet and hadron measurements
favorable statistics and S/B conditions
higher high pT statistics than p0 at RHIC
better direct/inclusive g ratio than at LHC
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

18. potential Japan/Asia contributions
sPHENIX “baseline” proposal to US-DOE
(vertex tracker +) hadron calorimeter + EM calorimeter
other funding required for inner(/outer?) detectors
charged particle tracking (e.g. silicon trackers)
full jet reconstruction
energy re-distribution at low z
g/p0/e identification (e.g. pre-shower detector)
direct g–jet correlation
di-electron
m identification (inside or outside of calorimeters?)
di-muon
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki

19. summary and concluding remarks
direct g non-suppression in Au+Au re-confirmed
ultimate reference trigger for quark energy loss
energy loss and re-distribution observed via g–h
high z (low x) suppression; low z (high x) enhancement
wider away (jet) side enhancement at lower z
naïve scenario consist so far, to be tested further
measurements w.r.t. initial parton and leading hadron
direct g–jet correlation in Au+Au awaited
further prospects:
reconstructed jet: baseline established in p+p, d+Au
sPHENIX for high pT g and hadron w/ high statistics/rate
Oct.22, 2012
HPT’12 – Jet/Photon/Hadron Correlations at RHIC-PHENIX – K.Shigaki