# Presentation: 332095

## Energy and B dependence of J/ production and suppression

- Abigail Bickley
- University of Colorado
- June 5, 2006

## Relevance to workshop?

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## J/ as a Hard Probe

- Quarkonia Production -
- 	Hard scattering processes result in the production of heavy quark pairs that interact with the collision medium during hadronization
- In medium interactions convey information about the fundamental properties of the medium itself

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Original Signature: Matsui & Satz

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Original Signature: Matsui & Satz

- “It is concluded that J/ suppression in nuclear
- collisions should provide an unambiguous signature
- of quark-gluon plasma formation.”

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Suppression Mechanism

- J/ Suppression Models:
- Heavy quarkonia are formed only during the initial hard nucleon-nucleon collisions
- Subsequent interactions only result in additional loss of yield
- Color Screening:
- Color charge of one quark masked by the surrounding quarks
- Prevents cc-bar binding in the interaction region
- Characterize by Debye screening radius (rD)
- If the screening radius is smaller than the J/ radius then the quarks are effectively masked from one another

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Both the screening and J/ radii are temperature dependent
J/ radius: (rJ/)
T=0: 
Radius dominated by confining potential
 0.2 ≤ rJ/ ≤ 0.5 fm
T≥Tc: 
Include color screened coulombic potential
0.5 ≤ rJ/ ≤ 1.3 fm
Screening radius: (rD)
Calculated from lattice QCD
Tc fixed at 200 MeV
rD ~ 0.2 fm

- J/ radius: (rJ/)
- T=0:
- Radius dominated by confining potential
-  0.2 ≤ rJ/ ≤ 0.5 fm
- T≥Tc:
- Include color screened coulombic potential
- 0.5 ≤ rJ/ ≤ 1.3 fm
- Screening radius: (rD)
- Calculated from lattice QCD
- Tc fixed at 200 MeV
- rD ~ 0.2 fm

- T/Tc = 1.5
- Upper bound for rD in
- dynamical quark system

- Correlation Length (fm)

- Temperature (MeV)

- Screening Radius

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Recent Lattice Calculations

- Temperature dependence of screening radius shows no strong transition at Tc
- No significant reduction in J/ mass or peak strength observed up to 1.5 Tc
- J/ suppression may not turn on until T > 2 Tc

- Datta et. al., J.Phys. G30 (2004) S1347.

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Competing J/ Production Effects

- Normal nuclear absorption:
- 	J/ breakup by nucleons in the final state resulting in charm hadrons
- Shadowing:
- 	Accounts for parton distribution modifications relative to free protons
- 	Affects parton distribution function before collision occurs
- Color Screening:
- 	In deconfined medium resonance interactions needed to convert cc pairs to J/’s are prohibited
- Comover Interactions:
- 	 J/ interactions with secondary hadrons results in dissociation
- 	Suppression mechanism that does not require deconfined medium
- Parton Induced Dissociation:
- 	Breakup of J/ due to in medium parton interactions
- J/ Recombination:
- 	Regeneration of J/’s from off-diagonal c and c pairs
- And many others....

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Recombination Mechanism

- Recombination Models:
- In central heavy ion collisions more than one c-cbar pair is formed
- RHIC: 10-40
- LHC: 100-200
- Regeneration of J/ pairs possible from independently produced c and cbars
- Leads to an enhancement of J/ yield (or less dramatic suppression)
- Results in modified rapidity and pT spectra
- Comments:
- On what time scale does this process occur?
- What is a reasonable path length to assume the quarks traverse to recombine?

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## SPS Environment

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## SPS Experiments: NA38,50,51,60

- Kinematical coverage:
- Acceptances:
- Species:

-  2.92 <  *y**lab**  *< 3.92
-  | cos ***cs *|  <  0.5
-  *Acc (J/****)* = 12.5%
* **Acc (DY)  = *13.8%  (for 2.9 < M < 4.5 GeV/c2)
-  p+p, p+d, p+C, p+Al, p+Cu, p+W, p+U, O+Cu,
-   S+Cu, O+U, S+U, In+In, Pb+Pb

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## SPS Light Ions

- All data rescaled to 200GeV
- Glauber fit of pA data:
- O+Cu, O+U and S+U not included in fit
- Fit used as normal nuclear absorption reference for heavy ion data

- Kluberg, Hard Probes 2004.

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## NA50 Results - Pb+Pb

-  Plot ratio of cross sections from J/ and Drell-Yan:
-  identical experimental biases, 	      	    inefficiencies,
- 	    selection criteria,
- 	    analysis cuts
-  Normal Nuclear Absorption from:
-   p+A data at 450 and 400 GeV
-   S-U at 200 GeV
-   abs = 4.2 ± 0.4 mb

- ±

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## NA50 Results - Pb+Pb

-  Plot ratio of cross sections from J/ and Drell-Yan:
-  identical experimental biases, 	      	    inefficiencies,
- 	    selection criteria,
- 	    analysis cuts
-  Normal Nuclear Absorption from:
-   p+A data at 450 and 400 GeV
-   S-U at 200 GeV
-   abs = 4.2 ± 0.4 mb
-  Summary:
- Ratio is “normal” for peripheral collisions, but becomes more and more “abnormal” with increasing centrality

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## NA60 Results - In+In

-  The S-U, In-In and Pb-Pb data point do not overlap in the L variable
-  The J/ suppression patterns are in better agreement in the Npart variable

- Arnaldi, Quark Matter 2005

- Arnaldi, Quark Matter 2005

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## RHIC Environment

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## STAR Capabilities

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## The PHENIX Experiment

- J/  + -
- p > 2GeV/c
-  1.2 < |y| < 2.2
-  

- J/  e+ e-
- p > 0.2GeV/c
-  || < 0.35
-  

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## PHENIX Data

- Run      Species    s1/2 [GeV ]     NTot         Data Size
- 01    	Au+Au      130          	  10M           3 TB
- 02   	Au+Au      200        	170M         10 TB
-             p+p            200         	  3.7G         20 TB
- 03       	d+Au         200         	  5.5G         46 TB
-             p+p            200         	  6.6G         35 TB
- 04    	Au+Au      200         	  1.5G       270 TB
- 	Au+Au        62         	  58M         10 TB
- 05	Cu+Cu	      200         	  8.6G	      173TB
- 	Cu+Cu         62        	  0.4G         48 TB
- 	Cu+Cu      22.5           	    9M           1 TB
- 	p+p            200          	   85B       262 TB
- 06	p+p	      200	    ?		?
- 	p+p	        62	    ?		?
- 	p+p	     22.5	    ?		?

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Comparing Systems and Energies

- PHENIX data:
- Au+Au 200GeV
- Cu+Cu 200GeV
- Cu+Cu 62GeV
- p+p 200GeV
- d+Au 200GeV
- Nuclear Modification Factor (RAA):
- Scale measured invariant yield by invariant yield found in p+p collisions at the same energy
- Account for differing number of nucleons by scaling by the number of binary collisions

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## PHENIX - p+p

- Consistent with trend of world’s data and with the Color Octet Model calculation

- Phys. Rev. Lett. **96**, 012304 (2006).

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## PHENIX - d+Au

- Used to probe cold nuclear matter effects
- Absorption of J/ by nuclear matter
- Modification of PDF due to possible gluon shadowing

- PHENIX data compatible with:
-   weak gluon shadowing
-   weak absorption : 1 mb

- Data

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Energy comparison at forward rapidity

- Cu+Cu, √s = 200GeV and 62GeV, 1.2 < |y| < 2.2

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## System size comparison at forward rapidity

- Au+Au and Cu+Cu, √s = 200GeV, 1.2 < |y| < 2.2

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## System size comparison at mid rapidity

- Au+Au and Cu+Cu, √s = 200GeV, |y| < 0.35

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## PHENIX Data & CNM Models 

- Cold nuclear matter models

- R. Vogt nucl-th/0507027

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## PHENIX Data & Suppression Models

- Suppression models w/o regeneration

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

**Notes:**
Update models

## PHENIX Data & Regeneration Models

- Suppression models with regeneration

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

**Notes:**
Update models

## Rapidity Dependence

- Shape of rapidity dependence of J/ yield consistent as a function of centrality
- No difference observed between Cu+Cu and p+p data distributions at 200GeV
- Rapidity narrowing predicted by recombination models clearly not present

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## NA50 & PHENIX Comparison

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Sequential Dissociation

- survival probability relative to normal nuclear matter

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Sequential Dissociation

- Show real Au+Au systematic errors - pt-to-pt and global scale
- (Note: real systematic errors associated with SPS data exist also!)

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Sequential Dissociation

- Shift dAu baseline down and AuAu points up by the systematic

- Scale Change!

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Sequential Dissociation

- Shift dAu baseline up and AuAu points down by the systematic

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## RHIC Future

- Run 7: high statistics Au+Au 200GeV, x4 luminosity
- Run 8: high statistics d+Au 200GeV, x10 luminosity
- STAR Detector Upgrades:
- Full barrel ToF
- New TPC FEE
- Silicon Tracking
- PHENIX Detector Upgrades
- Reaction Plane Detector
- Si Vertex Detector
- Nosecone Calorimeter
- RHIC Upgrades
- Increased luminosity
- Increased species

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## LHC Environment

| Collision System | sNN
(TeV) | L0
(cm-2s-1) | Run Time
(s/yr) | geon
(b) |
| --- | --- | --- | --- | --- |
| p+p | 14.0 | 1034 | 107 | 0.07 |
| Pb+Pb | 5.5 | 1027 | 106 | 7.7 |

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## LHC Environment

- ** HI Energy = 27.5 x RHIC

| Collision System | sNN
(TeV) | L0
(cm-2s-1) | Run Time
(s/yr) | geon
(b) |
| --- | --- | --- | --- | --- |
| p+p | 14.0 | 1034 | 107 | 0.07 |
| Pb+Pb | 5.5 | 1027 | 106 | 7.7 |

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## LHC Experiments

- CMS

- ATLAS

- ALICE

- ALICE:  J/++-, 2.5<||<4.0
- 	   J/  e++e-, || < 0.9
- CMS:     J/  ++-, || < 2.4
- ATLAS: J/  ++-, || < 2.5

**Si Tracker**
**including Pixels**

**ECAL**

**HCAL**

****** ****chambers**

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Projected Yields

- RHIC:
- assume 12 weeks physics run and collision vertex range of ± 10 cm
- Longer dedicated HI running time & greater luminosity
- LHC:
- Estimated yields for a 106 s Pb+Pb run with 500 b-1 integrated luminosity
- Charm and bottom cross sections greatly enhanced over RHIC energies
- All numbers from RHIC II Heavy Flavor Working Group Report

| Signal | RHIC I
PHENIX | RHIC I
STAR | RHIC II
PHENIX | RHIC II
STAR | LHC
ALICE | LHC
CMS | LHC
ATLAS |
| --- | --- | --- | --- | --- | --- | --- | --- |
| J/  e+e
J/   | 3,300
29,000 | 16,000
- | 45,000
395,000 | 220,000
- | 9,500
740,000 | -
24,000 | -
8k-100k |
|  ́ e+e- 
 ́  | 60
520 | 23,000
- | 800
7100 | 29,000
- | 190
14,000  | -
440  | -
1.4k-1.8k  |
|  e+e- 
  | 30
80 | 6,600
- | 400
1,040 | 8,300
- | 2,600
8,400  | -
26,000  | -
15,000  |

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Summary

- J/ production and suppression is a much more complicated process than originally conceived in the Matsui & Satz paper
- Only through measurements over a large range of energies and system sizes have we been able to begin to understand the J/
- The similarities between the suppression observed at the SPS and RHIC is striking
- Recombination of uncorrelated quarks?
- Sequential dissociation of charmonium states?
- Future runs at RHIC and LHC will shed light on these processes .... the excitement continues!

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Backup

## SPS J/’ and ’ Comparison

*J/***  and ***’*  suppression with “normal nuclear absorption”

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## J/ polarization in In+In

- Polarization is related to quarkonium production mechanism
- NRQCD predicts strong transverse polarization at large pT
- Increase in polarization could signal QGP onset
- QGP screens non-perturbative effects
- J/ from plasma region should be polarized according to perturbative QCD

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## J/ polarization in Au+Au @200 GeV

- J/ polarization helps discriminate between production mechanisms
- measured in central arm (|y|<0.35) in Au+Au @200GeV
- polarization is consistent with 0 within error bars

- : angle between lepton momentum in J/psi rest frame and J/psi momentum in lab frame

**Polarisation measurement: ***N(****) = A[1+****cos**2****]*

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## SPS and RHIC pT Distributions

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Cross sections vs pT (p+p, d+Au)

- Cross sections vs pT (p+p, d+Au)

- Fits to                                   used to extract <pT>2

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Cross section vs Rapidity (p+p)

- Good agreement with PYTHIA shape
- These are Run-3 data
- Run-5: ~ x 10
- Run-6:~ Run-5 today, expected to double

- #J/ψ’s:  ~400 (), ~100 (ee)

**√****s = 200 GeV**

**PRL **_**96**_**, 012304 (2006)**

- Rapidity

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Invariant yields vs pT (A+A)

- Invariant yields vs pT (A+A)

- Cu+Cu (|y|[1.2,2.2])

- Au+Au (|y|[1.2,2.2])

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Transverse Momentum Dependence

- fit to extract <pt2>

- Cu+Cu 200GeV

- Cu+Cu 200GeV

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Transverse Momentum Dependence

- Data: <pT2> is consistent with flat as a function of centrality
- Theory*: Red shows NLO calculation without recombination
- 	Blue shows effect of including J/ produced via          recombination

- * R.L. Thews, PHENIX Muon Workshop, June 13, 2005.

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Mean transverse momentum vs Ncoll

- Mean transverse momentum vs Ncoll

- Added Thews predictions for **Au+Au** and **Cu+Cu** collisions @200GeV. Solid (dashed) is with (without) regeneration.

- all PHENIX J/ data

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Npart Scaling

- J/ yield scaled by the number of participants is consistent with flat when plotted versus centrality

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Nuclear Modification Factor:

- Rapidity comparison in Au+Au 200 GeV

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Nuclear Modification Factor:

- Rapidity comparison in Cu+Cu 200 GeV

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Invariant Mass Plots

- Raw J/ signal visible above the combinatorial and physical
- background of like sign dimuon and dielectron pairs

- PHENIX

- PHENIX

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Invariant Mass Plots

- Like sign subtraction method used to isolate J/ signal
- Integrate over mass range of 2.6-3.6 GeV/c2

- PHENIX

- PHENIX

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006

## Acceptance * Efficiency

- Detector geometrical coverage
- Detector hardware performance
- Trigger efficiency
- Reconstruction efficiency

- PHENIX

- Abigail Bickley, RHIC & AGS Users Meeting

- June 5, 2006