highlights from phenix ii: photons and leptons

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


• 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)


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)


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)


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


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)


• 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)).


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


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 −

−=

RvvR

votonBGotoninc

otondi

Session XV: Kentaro Miki

Direct v2 Min Bias Au+Au 200 GeV (Run 4)


-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


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


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


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


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-


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


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


Measured p+p Mee compared to Cocktail

• Cocktail filtered in PHENIX acceptance

• Charm, Bottom, DY contributions from PYTHIA

• Excellent agreement!

arXiv:0802.0050


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 MorinoDonny Hornback


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


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:


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.


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


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 )


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


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


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

highlights from phenix ii: photons and leptons

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