Highlights from PHENIX II: Photons and Leptons Terry Awes, ORNL For the PHENIX collaboration.
-
date post
19-Dec-2015 -
Category
Documents
-
view
224 -
download
3
Transcript of Highlights from PHENIX II: Photons and Leptons Terry Awes, ORNL For the PHENIX collaboration.
Highlights from PHENIX II:Photons and Leptons
Terry Awes, ORNLFor the PHENIX collaboration
Terry Awes, ORNL - QM08, Jaipur India Slide:2
Photons and Leptons• Penetrating probes that carry
information about their production.
• Rare processes– Need large data samples
• Large backgrounds– Need precise background
determination • Background from decays of and • Electrons from conversions • Combinatorial Backgrounds
• Theme: Towards Higher Accuracy
Terry Awes, ORNL - QM08, Jaipur India Slide:3
• Improved Statistical errors – Au+Au
Statistics: • 30 : 10 : 1 ( Runs 7 : 4 : 2 )
• Improved Systematic errors– More statistics– Two EMCals
More Precise Measurements
arXiv:0801.4020
Au+Au 200 GeV (Run 4)
Terry Awes, ORNL - QM08, Jaipur India Slide:4
Improved p+p Reference Data
• PHENIX 62 GeV p+p cross section approx. 2 times higher than ISR average.
• 200 GeV p+p data 10x (with Run5)
J.Phys.G31:S491 (2005)
p+p 62 GeV (Run 6)
Terry Awes, ORNL - QM08, Jaipur India Slide:5
Nuclear Suppression Dependence on:
Cu+Cu 22,62,200 GeV (Run 5)
• Model calculations indicate quenching expected at sNN = 22 GeV, but Cronin effect dominates
• Species dependence to probe space/time of suppression
arXiv:0801.4555
Energy Particle Species Au+Au 200 GeV (Run 4)
Terry Awes, ORNL - QM08, Jaipur India Slide:6
Dependence of Nuclear Suppression
• RAA scales with Npart at same sNN
– Some indication for “higher order” effects
• Approximate scaling with <L>
• Use RAA(Npart, sNN, Species, Pathlength) to illuminate models
Session I: Klaus Reygers
PHENIX PRC 76 034904
NPart Pathlength
Direct Photons
Terry Awes, ORNL - QM08, Jaipur India Slide:8
Towards inclusive ( contribution)
• Universal mT-scaling – Independent of centrality in Au+Au
Poster: B.Sahlmuller
Au+Au 200 GeV
p+p systematics
PRC 75, 024909 (2007)
PHENIX Preliminary
PRC 75, 024909 (2007)
Terry Awes, ORNL - QM08, Jaipur India Slide:9
• Run 4 (QM06): High pT suppression
– Isospin (PDF) effect (+ ?)
PHENIX Preliminary
Direct Au+Au: Direct = Inclusive-Decay
• Run 2: No suppression -> Jet quenching (PRL 94, 232301 (2005)).
Terry Awes, ORNL - QM08, Jaipur India Slide:10
Direct RAA ResultsCentral Cu+Cu 200 GeV (Run 5) Direct RAA vs Npart
Session VIII: Takao Sakaguchi
PHENIX Preliminary
PHENIX PreliminaryMin Bias Au+Au 62 GeV (Run 4)
• Direct RAA 1• Is there other evidence for nuclear effects?
– Reduced/enhanced radiation due to jet quenching
Terry Awes, ORNL - QM08, Jaipur India Slide:11
Direct v2 : Au+Au 200 GeV
• Interested in sign of direct v2 (at high pT): – Positive == parton emission quenched– Negative == parton emission (Brems.) enhanced
• Results suggest positive v2
1
* _2
.2.
2 −−
=R
vvRv
photonBGphotonincphotondir
Session XV: Kentaro Miki
Direct v2 Min Bias Au+Au 200 GeV (Run 4)
Terry Awes, ORNL - QM08, Jaipur India Slide:12
-h Correlations
“measures” recoil parton momentum– Measure fragmentation function D(Z)
-h p+p 200 GeV (Run 5)
~D(z)
2triggerT
triggerT
partnerT
Ep
ppx
⋅−≡
Session XV: Matthew Nguyen
Poster: A.Hanks
Use Near Side peak to determine direct associated with h, I.e. fragmentation photons
J/ Production
Terry Awes, ORNL - QM08, Jaipur India Slide:14
J/ d+Au: Cold Nuclear Matter
• Increased Run 5 p+p statistics (x10 Run 3)
• Improved & consistent p+p and dAu analysis– Improved alignment, resolution, yield
extraction,… – Cancellation of systematic errors in RdAu
• Result: CNM = Shadowing(EKS) + Breakup
= 2.8 mb– Consistent within errors with previous
results– and with Breakup=4.2+/-0.5mb (SPS result)
J/ RdAu 200 GeV
Session VI: Matthew WysockiarXiv:0711.3917
+1.7-1.4
Terry Awes, ORNL - QM08, Jaipur India Slide:15
J/ Au+Au: CNM Effects
• Large errors still (need Run 8 d+Au, Run 7 Au+Au)– Comparison suggests more forward suppression beyond CNM than at
mid-rapidity– BUT models shown don’t describe RdAu impact parameter dependence
J/ RAuAu 200 GeV (Run4)
arXiv:0711.3917
|y| < 0.35 1.2 < |y| < 2.2
Terry Awes, ORNL - QM08, Jaipur India Slide:16
J/ RAA Cu+Cu and Au+Au• Approx 2x more J/ in Cu+Cu
sample than Au+Au sample– More precise Npart<100 info
• Curves show RAA prediction from ad hoc CNM fit to RdAu separately at y=0 and y > 1.2
• CNM from RdAu fit describes suppression for Npart < 100.
J/ RAA 200 GeV
Session XVIII: Susumu Oda
arXiv:0801.0220
RdAu constraints are not sufficient to say if suppression beyond cold nuclear matter is stronger at forward rapidity
Terry Awes, ORNL - QM08, Jaipur India Slide:17
J/ <pT2> Cu+Cu and Au+Au
• No (or modest) pT broadening of J/ – Conspiracy of low pT suppression and recombination?
Session XVIII: Susumu Oda
arXiv:0801.0220
Low Mass e+e-
Terry Awes, ORNL - QM08, Jaipur India Slide:19
Electron Pair Mass Spectrum p+p
• Combinatorial Bkground subtraction error 0.25%– Confirmed with special
convertor runs
• Correlated unlike (and like) pairs due to jet and Dalitz photon pair conversions
Mee p+p 200 GeV (Run5)
Unlike sign
Like sign
arXiv:0801.0220
Terry Awes, ORNL - QM08, Jaipur India Slide:20
Hadronic Cocktail to Calculate Mee
• Based on PHENIX measurements– (Light VM See
Session XXIII Y. Nakamiya)
• Fit to pion spectrum provides excellent fit to all other mesons with MT-scaling assumption– MT-scaling works very
well
arXiv:0802.0050
Terry Awes, ORNL - QM08, Jaipur India Slide:21
Measured p+p Mee compared to Cocktail
• Cocktail filtered in PHENIX acceptance
• Charm, Bottom, DY contributions from PYTHIA
• Excellent agreement!
arXiv:0802.0050
Terry Awes, ORNL - QM08, Jaipur India Slide:22
Heavy Quarks in p+p from e+e-
c dominant
b dominant
After subtraction of Cocktail -Fit to a*charm+ b*bottom (with PYTHIA shape)
arXiv:0802.0050
• Good agreement with single e results
• Also new analyses via e-h coincidences, single muons, and direct charm measurement– See talks:
Session XIV:
Yuhei Morino
Donny Hornback
Terry Awes, ORNL - QM08, Jaipur India Slide:23
Bottom Measurement
• Charm and bottom spectra both x above FONLL calculations– But ratio is in good agreement with FONLL
Session XIV:
Yuhei Morino
p+p 200 GeV Charm and bottom extracted via e-h mass analysis
Terry Awes, ORNL - QM08, Jaipur India Slide:24
Heavy Flavor via non-photonic Electrons• HF strongly suppressed, Significant v2
– Implies high density, small diffusion coefficient
– Estimate /s = (1.3-2)/4– Very close to conjectured limit
PHENIX : PRL98, 172301 (2007)
Session XIV: Ralf Averbeck
Poster: A.DionPreliminary Run 7 HF v2 result:
Terry Awes, ORNL - QM08, Jaipur India Slide:25
Au+Au Mee compared to Cocktail• Data and Cocktail
absolutely normalized
– Cocktail normalized to Au+Au measurements
• Except ccbar
• Low mass excess– 150 < Mee < 750– X 3.4±0.2(stat.)
±1.3(syst.)±0.7(model)
• Intermediate mass agreement
arXiv:0706.3034
– Thermal contribution perhaps if ccbar mass spectrum softened by rescatt.
Terry Awes, ORNL - QM08, Jaipur India Slide:26
PT Dependence of Au+Au Mee
• Low Mass excess is a low pT enhancement– Huge excess at
lowest pT
– Late Phase info
0 < pT < 8 GeV/c 0 < pT < 0.7 GeV/c
0.7 < pT < 1.5 GeV/c 1.5 < pT < 8 GeV/c
Session XI:
Alberica Toia
PHENIX Preliminary • Still significant at high pT
Terry Awes, ORNL - QM08, Jaipur India Slide:27
High pT Direct Yield from *
• Virtual with pT >> mee should be produced directly with a rate and mass distrib. that follows a “Dalitz” form fdir with MHad->oo
• Extract Direct * “excess” as fraction r of fdir needed to describe low mass excess
• That direct * fraction of inclusive * (mostly and ) should be the same as the real fraction of inclusive (mostly and )
Terry Awes, ORNL - QM08, Jaipur India Slide:28
Direct via * for p+p, Au+Au• New p+p result with *
method agrees with NLO pQCD predictions, and with statistical method at high pT
– Confirmation of the method
• For Au+Au (QM05 result) there is a significant low pT excess above p+p expectations– Interpreted as thermal
emission -> Initial T
Session XV: Torsten DahmsarXiv:0801.xxxx
Terry Awes, ORNL - QM08, Jaipur India Slide:29
Summary
• More precise studies of sQGP matter – Systematics of RAA
-h correlations
– Dilepton excess
• Initial T and evolution– Low pT direct excess
– Heavy Flavor– J/ |y| < 0.35
Terry Awes, ORNL - QM08, Jaipur India Slide:30
PHENIX Data SetsYear Species √s [GeV ] ∫Ldt Ntot (sampled) Data Size
Run1 2000 Au - Au 130 1 µb-1 10 M 3 TB
Run2 2001/02 Au - Au 200 24 µb-1 170 M 10 TB
Au - Au 19 < 1 M
p - p 200 0.15 pb-1 3.7 B 20 TB
Run3 2002/03 d - Au 200 2.74 nb-1 5.5 B 46 TB
p - p 200 0.35 pb-1 6.6 B 35 TB
Run4 2003/04 Au - Au 200 241 µb-1 1.5 B 270 TB
Au - Au 62.4 9 µb-1 58 M 10 TB
Run5 2005 Cu - Cu 200 3 nb-1 8.6 B 173 TB
Cu - Cu 62.4 0.19 nb-1 0.4 B 48 TB
Cu - Cu 22.4 2.7 µb-1 9 M 1 TB
p - p 200 3.8 pb-1 85 B 262 TB
Run-6 2006 p - p 200 10.7 pb-1 233 B 310 TB
p - p 62.4 0.1 pb-1 10 B 25 TB
Run-7 2007 Au - Au 200 725 µb-1 4.6 B 570 TB
Run-8 2007/08 d - Au 200
p - p 200/500