# Presentation: 497700

## PHENIX Results

- Y. Akiba (RIKEN Nishina Center)
- for PHENIX Collaboration
- RHIC/AGS User’s meeting
- 2008.05.29

## The RHIC Physics Program

**The RHIC Physics Program**

**RHIC**

## PHENIX Data-Sets

**Collided 4 different species in 8 years:  AuAu, dAu, pp, CuCu**
**6 energies run:  9.2 GeV, 19 GeV, 22.5 GeV, 62.4 GeV, 130 GeV, 200 GeV**

## PHENIX publications

- 67 papers published since 2001
- Phys. Rev. Lett.	41
- Phys. Rev. C	19
- Phys. Rev. D	5
- Phys. Letter B	2
- Nucl. Phys. A	1
- 	(white paper)
- Total citation: ~5900
- 500+		1
- 250-500		5
- 100-250		11
- 50-100		18
- 19 +3 papers published + accepted since January 2007
- PRL	9 +1
- PRC	7 +2
- PRD	2
- PLB	1
- 8 papers in review

- PHENIX “White Paper” is now a “Renowed” (500+) status, with total of 504 citation.

## Proton Spin

- Well measured
- only ~30% of spin

- Spins + orbital angular momentum need
- to give the observed spin 1/2 of proton

**Notes:**
Proton is a bag of bound quarks and gluons under strictures of QCD
Proton is spin 1/2 object so pieces must come together -> written as “sum rule”
Delta-q is measured, delta-G is not 

## π0 ALL :   work horse for G(x)

- pQCD works for pT>2GeV/c

- RUN5 resutls: PRD76 (2007) 051106

-  0 ALL  constraint on G

## RUN6 0 ALL

- Final RUN6 results will be published soon
- Gives much stronger constraint on G

## More ALL measurements

- Many independent probes to understand gluon spin

- NEW

- NEW

- NEW

- NEW

##  Forward 0 AN at large xF with MPC

## AN of muons from charm/bottom decays

- AN of charm decay muons is measured for the first time

- “Max” value of AN of charm is
- not well constrained

- NEW

## 3D source imaging

- 3D source imaging reconstructs source parameters

- reverse engineer the correlation function by an input source function.
- The analysis suggests that there is a long tail of the source distribution
- Solutoin of the long-standing “HBD puzzle”?

- arXiv:0712.4372, PRL accepted

## Scaling of v2 of hadrons

- More data on v2(pT) of hadrons are accumulated
- When v2/nq vs KET/nq (KET=transverse kinetic enery), all data points are on a universal curve, suggesting that v2 developed in partonic stage

- PRL98,162301(2007)

## More on the scaling of v2: phi flow

**the number of quark (nq) scaling.**

- PRL99, 052301 (2007)

## v2 of Direct photon and J/e+e-

- v2 of Direct photon and J/e+e-

- First ever at RHIC,
- v2 - J/μ+μ- coming soon

- J/Psi coalescence ?

- NEW

- PHENIX preliminary

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

- 	Sign of direct  v2 (at high pT):
- Positive == parton emission quenched
- Negative == parton emission (Brems.) enhanced

## v4 - scales with v2

- V4

- pT (GeV/c)

- V4/(nq)2

- KET /nq (GeV/c2)

- KET (GeV/c2)

- v2  scales with nq,    v4  with nq2  partonic degree of freedom

- V4

- PHENIX preliminary

- NEW

## π0 pT spectra  at √sNN = 200 GeV

- RAA measurements now extends to 20 GeV/c

## Quantitative analysis

- Comparison with GRV model: dNg/dy=1400

- arXiv:0801.1665 PRC accepted

## RAA beam energy dependence (Cu+Cu) 

-  Cu+Cu 22,62,200 GeV (Run 5)

- Model calculations indicate quenching expected at *s*NN = 22 GeV, but Cronin effect dominates
- Species dependence to probe space/time of suppression

- arXiv:0801.4555

- 

## RAA of hadrons and direct photon (AuAu 200GeV)

- RAA of hadrons and direct photon (AuAu 200GeV)

- Same suppression pattern for 0 and : Consistent with parton energy loss and fragmentation  in the vacuum
*R*AA for ‘s larger than 0 *R*AA for 2 < *p*T < 5 GeV/*c. Why?*
- Ncoll scaling for direct  (except for highest pT point?– Isospin effect?)

## More Direct photon RAA Results

- Central Cu+Cu 200 GeV (Run 5)

-  Direct  RAA vs Npart

- PHENIX Preliminary

- PHENIX Preliminary

- Min Bias Au+Au 62 GeV (Run 4)

- Direct photon RAA  1
- Is there other evidence for nuclear effects?
- Reduced/enhanced radiation due to jet quenching

- NEW

- NEW

## Modification of jet correlation

- Two particle of two high pT track (jet correlation) is modified in central Au+Au collisions.
- Many theory attempts to explain these effect
- Probing the medium response to fast partons

- PRL97,052301 (2006)

- Au+Au

## More detailed study of jet correlation

**PRL98, 232302 (2007)**

**Notes:**
This slide will take lots of explanation. 

Start with the upper left-hand plot. Explain the shape of the 2-particle correlations, and the flat away side means subtracting any v2 will lead to a dip. Peak is about ~1 radian displaced from pi, in qualitative agreement with what might be expected from models of collective medium excitation. Introduce the centrality plots for AuAu and CuCu. 

Explain that we characterize the character of the away side using RMS and KURTOSIS, explain legend and trends on plot. (rms rises and levels off while kurtosis drops and levels off) Emphasize the high level of agreement between the different colliding systems and energies (very surprising). Features depend on Npart but not species or energy. 

Also characterized by a “peak angle parameter” in a fit to two Gaussians. Describe behavior (rises and levels off). 

Data is consistent with sound or shock waves, but not Cerenkov (should disappear for increasing momentum of associated hadrons, and it doesn’t) This isn’t shown in th eslide but refer to talks/posters for details. 

## jet correlations vs reaction plane

- unchanged near-side peak in the final jet functions when moving away from Reaction plane, indication for away side modification.

## -h Correlations

-  “measures” recoil parton momentum
- Measure fragmentation function D(Z)

- -h  p+p 200 GeV (Run 5)

## J/ suppression in Au+Au

- J/ suppression in Au+Au

- High statistics measurement of J/ in AuAu in wide rapidity range
- Mid-rapidty J  ee
- Forward rapidty J/
- Strong suppression of J/ is observed
- Consistent with the prediction that J/s are destroyed in de-confined matter
- Surprisingly, the suppression is stronger at forward rapidity than in mid-rapidity
- J/ formation by recombination of charm pairs in deconfined matter?

- PRL98,172301 (2007)

## RAuAu (run 4) = RAuAu (run 7)

- Forward rapidity only (for now)
- More bins at higher centrality
- Confirm the trend
- RAA(y≈1.7) < RAA(y≈0)

- NEW

## J/ d+Au: Cold Nuclear Matter

- Increased Run 5 p+p statistics (x10 Run 3) as baseline
- 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)

- PRC77_024912 (2008)

- +1.7
- -1.4

- J/ RdAu 200 GeV

## 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

- arXiv:0801.0220

- RdAu constraints are **not sufficient** to say if suppression beyond cold nuclear matter is stronger at forward rapidity

## Heavy flavor electron RAA and flow

-  Two models describes strong
-     suppression and large v2
-  Rapp and Van Hee
-  Moore and Teaney
-  From model comparison,
-     viscosity to entropy ratio /s
-     can be estimated
- 	*D**HQ* × 2π*T* = 4 - 6
- 	*D**HQ* ~ 6 x /(+p) = 6 x /*Ts*
-           /*s* ~ (4/3 – 2)/4
-  The estimate of /s is close
-    to the conjectured bound
-    1/4from AdS/CFT

**PRL98,172301 (2007)**

- Contraints on /s

## Bottom Measurement

- Charm and bottom spectra both x above FONLL calculations
- But ratio is in good agreement with FONLL

- p+p 200 GeV   Charm and bottom extracted via e-h mass analysis

- NEW

- NEW

## total cross section of charm and bottom

**total cross section of charm and bottom**

- √s dependence of cross section with NLO pQCD
- agrees with data

- NEW

## Is bottom also suppressed? Does it flow?

- p+p data indicates that a large contribution of b for pT>2 GeV/c
- The suppression in high pT is strong and new v2 data suggest significant flow of HF electron in high pT
- Is bottom also suppressed?
- Does bottom also flows?

- NEW

## e+e- pairs in p+p

- Cocktail filtered in PHENIX acceptance
- Charm, Bottom, DY contributions from PYTHIA
- Excellent agreement!

- arXiv:0802.0050

## e+e- pairs in Au+Au

- Data and Cocktail absolutely normalized
- Cocktail normalized to Au+Au measurements
- Except ccbar
- Low mass excess
- 150 < Mee < 750 MeV
- X 3.4±0.2(stat.) ±1.3(syst.)±0.7(model)

- arXiv:0706.3034

## PT Dependence of Au+Au Mee

- Low Mass excess is a low pT enhancement
- Huge excess at lowest pT
- Late Phase info

- NEW

## Enhancement of almost real photon

- Kinematic region of e+e- pairs
- m<300 MeV and 1<pT<5 GeV/c
- p+p
- Good agreement of p+p data and hadronic decay cocktail
- Small excess in p+p at large mee and high pT
- Au+Au
- Clear enhancement visible above for all pT

**1 < p****T**** < 2 GeV**
**2 < p****T**** < 3 GeV**
**3 < p****T**** < 4 GeV**
**4 < p****T**** < 5 GeV**

- arXiv:0804.4168

## Direct for p+p, Au+Au

- Direct for p+p, Au+Au

- New p+p result with * method agrees with NLO pQCD predictions, and with the measurement by the calorimeter
- For Au+Au there is a significant low pT excess above p+p expectations
- Excess is exponential in shape with inverse slope T~ 220MeV
- Thermal photons from hydrodynamical models with Tinit=300 – 600MeV at     0=0.6-0.15fm/c are qualitative agreement with the data.

- NLO pQCD (W. Vogelsang)

- Fit to pp

- exp + TAA scaled pp

- arXiv:0804.4168

## Constrain the properties and evolution of the matter

## Summary

- 2007-2008 is very productive for PHENIX
- Spin physics results
- Constraint on gluon polarization from pi0 ALL
- More new ALL measurements
- AN of forward pi0, heavy flavor decay muons
- Many heavy ion physics results
- 		3D imaging		Flow
- 		High pT hadrons	Jet correlation
- 		Direct photon		Heavy quark
- 		Dilepton		Thermal(?) Photon
- These results start to give constraint on the properties of the dense matter formed at RHIC