# Presentation: 264311

## Quarkonia Production in Cold and Hot Matters

- Raphaël Granier de Cassagnac
- LLR – École polytechnique / IN2P3
- Quark Matter 2008
- Jaipur, 2008, February 6th

## The normal introduction

- In 1986, Matsui & Satz predicted an “unambiguous” signature of QGP
- Onset of quarkonia melting above a certain temperature / energy density threshold
- _Exemple_ of assumed Td (but theorists still working on it) :

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**S. H. Lee, Next talk**

- Matsui & Satz, PLB178 (1986) 416

## Cold and hot matters @ SPS

- _Normal nuclear absorption alone _does a splendid job describing pA, SU and peripheral InIn and PbPb:
- σabs = 4.18 ± 0.35 mb
- Beyond is “anomalous suppression”
- InIn looks like an onset

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- NA60 preliminary

- σabs = 4.18 ± 0.35 mb

- NA50, EPJ C39 (2005) 335
- NA60, PRL99 (2007) 132302

- ± 10% global systematics

**Notes:**
« as good on onset as the experimental resolution of centrality allows »

## At SPS, J/ψ behave pretty much like the predicted golden QGP signature

- What about RHIC?

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## RAuAu (y≈0 in PHENIX) ≈ RPbPb (@ SPS)

- Lower rapidity RAA looks surprisingly similar, while there are obvious differences:
- At a given Npart, different energy densities...
- Cold nuclear matter effects (xBjorken, σabs...)
- ...

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- REDO
- Without forward

- PHENIX, PRL98 (2007) 232301
- SPS from Scomparin @ QM06

## RAuAu (y≈1.7) < RAuAu (y≈0) in PHENIX

- @ RHIC, more J/ψ suppression at forward rapidity !
- While energy density should be smaller...

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- REDO

- PHENIX, PRL98 (2007) 232301

## 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)

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- NEW

## RAuAu vs RCuCu @RHIC

- Final CuCu analysis
- Slightly below 1 in CuCu

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- PHENIX, arXiv:0801.0220

- PUB

- RAA(y~1.7)
- RAA(y~0)

**S. Oda, Session 18, Saturday**

## RCuCu (STAR, high pT) ≈ 1

**2 sigma J/****ψ**** signal in Cu+Cu**
**STAR = PHENIX charm spectra ******

**R****CuCu**** raising with p****T**

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- M.R. Cosentino,
- Poster 109

**Z. Tang, Session 18, Saturday**

- NEW

**Notes:**
Between 5 and 6 : 12 – 6 = 6 pm 4.2 is a 1.4 sigma signal (upper limit) 2 10–1 pm 10–1 
Between 6 and 8 : 17 – 7 = 10 pm 4.9 is a 2 sigma signal

## Various RXY(pT)

- Various RXY(pT)

- Several (hints of)             raising RAA(pT)
- RCP PbPb (NA50)
- RAuAu (PHENIX)
- RdAu (PHENIX)
- Several potential reasons:
- Leakage effect, J/ψ escape
- High pT J/ψ forming beyond QGP
- Cronin effect
- Raising xBj = less shadowing
- 0.02 to 0.05 from 0 to 9 GeV/c
-  See discussion in →
- Think about it...

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- PHENIX, arxiv:0711.3917 compared to
- Ferreiro, Fleuret, Rakotozafindrabe,
- arxiv: 0801.4949

- 1

- 2

- 3

**Notes:**
Ramello : 0708.1488 

## @ RHIC, more suppression at forward rapidity !

- Two possible _theoretical_ explanations...
- Hot : coalescence, regeneration
- Cold : saturation, shadowing

## I. Coalescence, regeneration

- Large variety of approaches, all justify:
- RAA(y=0) > RAA(y=1.7)
- (more c quarks to recombine at y=0)

- As an _example_

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**A. Andronic,**
**Session 22, Saturday**

**K. Tywoniuk, Session 22, Saturday**

- Capella, Tywoniuk et al.
- Fitting Cu+Cu, Au+Au,
- Mid and forward rapidity

**Notes:**
R. Rapp et al, PRL 92, 212301 (2004)

## II. A trick of cold matter ?

- Saturation could suppress forward J/ψ in AuAu
- First numerical estimate, _work in progress_...

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- NEW

**M. Nardi, Session 6, Tuesday**

- Experiment
- Saturation

- Normalisation here ?

- 0-20%

- 20-40%

- 40-60%

- 60-93%

- “Flat anomalous”
- suppression here ?

## How to move forward experimentally ?

- Be more open?
- Calm down?
- Broaden interest?
- Let it flow?
- Get excited?
- Get high?
- Be upset?
- Give up?

- (Measure cc to constrain regen.)
- (Better pA/dA reference)
- (in transverse momentum)
- (elliptically)
- (ψ’, χc)
- (in mass, looking at upsilons)
- (and search for onset)
- And move to the LHC?

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**Y. Zhang, **
**few minutes ago**

- Some progress on all these points at this meeting !

## 2. Cold matter

- New analysis of PHENIX dAu
- (and same pp reference as AA)
- Assuming two shadowing schemes, derive a breakup cross sections from RdA(y)
- σEKS ≈ 2.8 +1.7–1.4 mb
- σNDSG ≈ 2.2 +1.6–1.5 mb
- Proper error on σ is ≈ 2 mb
- And extrapolate to AuAu collisions 
- (Also available for CuCu)
- Mid and forward are correlated through shadowing scheme
- _If you believe this shadowing_, large anomalous suppression, larger at forward rapidity.

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**M. Wysocki, Session 6, Tuesday**

- PHENIX, arxiv:0711.3917

- PUB

- Forward rapidity

-  Midrapidity

## 2. Cold matter

- More model independent...
- In a Glauber data-driven model, propagate what we know from RdA(y,centrality)
- RAA(y,b) = Σi RdA (–y,bi1) x RdA(+y,bi2)
- No shadowing scheme nor absorption  scheme
- Mid and forward are not correlated, less model dependent  larger uncertainties (esp. y≈0)
- Anomalous suppression at least at forward rapidity!
- Anomalous suppression could be identical at midrapidity
- (No dCu, so no CuCu)

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**M. Wysocki, Session 6, Tuesday**

- RGdC, Quark Matter 06
- PHENIX, arxiv:0711.3917

- Survival = 38 +18– 22 %

- Survival = 55 +23–38 %

- Forward rapidity

-  Midrapidity

## 2. Cold matter again ?

- Fitting an effective break-up cross section (depending on y) and extrapolate to CuCu and AuAu...
- Do you agree that we have poor handle on the cold nuclear matter effect?

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- PHENIX, arxiv:0801.0220

**S. Oda, Session 18, Saturday**

- STOP

- PUB

## RHIC run 8 dAu ≈ 30 x run 3 !

- Let’s wait for this run analysis before to say more about cold matter (and derive decent survival probabilities)

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**Notes:**
80 nb –1 

## Look at other observables

- 3. pT broadening
- 4. Elliptic flow

## 3. pT broadening @ RHIC ? vs Npart ?

- Widely unknown initial charm production:
- Recombined RAA are poorly constrained...
- Instead look at pT:
- Hot: Inherited pT  should be lower than initial
- Cold: Cronin effect should broaden initial pT
- Cronin goes like:
- <pT2>AB = <pT2>pp + α x L

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- No strong <pT2> dependence...
- Modest rise at forward rapidity
- Could be broadening
- No need for recombination here

- PHENIX, arxiv:0801.0220

- Mid rapitidity

- Forward rapitidity

**Notes:**
No pA, single dA point, CuCu and AuAu

## 3. pT broadening @ RHIC ? vs thickness ?

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- No strong <pT2> dependence...
- Modest rise at forward rapidity
- Could be broadening
- No need for recombination here

- 2.7 sigma slope

- Widely unknown initial charm production:
- Recombined RAA are poorly constrained...
- Instead look at pT:
- Hot: Inherited pT  should be lower than initial
- Cold: Cronin effect should broaden initial pT
- Cronin goes like:
- <pT2>AB = <pT2>pp + α x L

- Mid rapitidity

- Forward rapitidity

**Notes:**
No pA, single dA point, CuCu and AuAu

## 3. pT broadening @ SPS ?

- Different scaling in pA and AA collisions
- Something else going on in AA?
- High pT J/ψ escape?

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- All data taken
- at 158 GeV!

- NEW

**R. Arnaldi, Session 18, Saturday**

## 4. J/ψ flow in PHENIX?

- 4. J/ψ flow in PHENIX?

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**C. Sylvestre, Session 18, Saturday**

- C.L. Silva,
- Poster 85

- If recombined, J/ψ should inherit the (rather large) charm quark elliptic flow
- First measurement by PHENIX:
- V2 = –10 ± 10 ± 2 ± 3 %
- Proof of principle
- Does not allow to elect best scenario

## 4. Elliptic flow in NA60 ?

- Seems large for In+In (no recombination)
- To be understood...

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**R. Arnaldi, Session 18, Saturday**

- Central In+In collisions

- Eccentric In+In collisions

- NEW

## Look at other particles

- 5. Feed down to J/ψ
- 6. Upsilons

## 5. Feed down to J/ψ(from pp collisions)

**ψ ****from ****ψ****’ = 8.6 ± 2.5%**

**ψ ****from ****χ****c**** < 42% (90% CL)**

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**S. Oda, Session 18, Saturday**

**Also measure of beauty cross section**
**ψ from B = 4 ****+**** – ****3****2**** %**

- NEW

**Y. Morino, Session 14, Friday**

- M. Donadelli,
- Poster 127

**Notes:**
P127 Marisilvia P85 Cesar P98 Han Liu

## 6. STAR upsilon’s

- Proof of principle: dozens of Y in p+p & A+A!
- Nuclear modification factor to come soon
- Suffers less from cold matter (x=0.02 to 0.1=EKS antishadow)
- (should be checked with run8 d+Au)
- Should measure (unseparated) excited states melting

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**D.Das, Session 22, Saturday**

## What else ?

- 7. Look for onsets
- 8. Go to LHC

## 7. Search for an onset? 

- 7. Search for an onset?

- Onset curves fit the midrapidity AuAu data...
- Chaudhury, nucl-th/0610031
- Gunji et al, hep-ph/0703061
- (after CNM subtraction)
- But so do smooth curves !
- Nagle nucl-ex/0705.1712
- Density threshold @ y=0 is incompatible with SPS onset
- Linnyk & al, nucl-th/0705.4443
- No onset @ y=1.7 ?
- Wait for run7 analysis            & CNM constraints!

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- Gunji et al, PRC 76 (2007) 051901

**T. Gunji, Session 18, Saturday**

- A.K. Chaudhury, nucl-th/0610031

- STOP

## 8. LHC ? 

- A new story will begin
- ↓ More J/ψ melting
- ↓ Larger shadowing / saturation effects
- ↑ Larger recombination (more pairs)
- If recombination prevails → golden signal
- If not, expect same or worse difficulties as at RHIC...
- (Also Upsilon’s story)

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**A. Andronic,**
**Session 22, Saturday**

- Example of prediction

## Anomalous conclusions

- J/ψ production is not (well and yet) understood at RHIC
- Forward/mid rapidity difference could be due to:
- Regeneration ?
- Saturation ?
- Something else ?
- However,  conservative cold matter approaches still gives significant anomalous suppression at least at forward rapidity...
- The hot matter is deconfining some quarkonia
- More to come soon
- dAu data ! Upsilon, ψ’ in AA collisions and much more...

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- M. Mishra
- P132

- H. Liu
- P98

**Notes:**
Last but not least !

## That’s all folks

- Back up slides...

## Density threshold ? No !

- J. Nagle, nucl-ex/0705.1712

- Onset curves fit the midrapidity data...
- Chaudhury, nucl-th/0610031
- Gunji et al, hep-ph/0703061
- (after CNM subtraction)
- So do smooth curves !
- Nagle nucl-ex/0705.1712
- Density threshold @ y=0 is incompatible with SPS onset or larger suppression @ y=1.7
- Linnyk & al, nucl-th/0705.4443

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## RdAu(y)

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## RdAu(centrality,y)

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## Regeneration ?

- Various coalescence / recombination approaches...
- Better match to data
- (look in particular Bratkovskaya’s)
- Depend a lot on poorly known cc reference
- But can accommodate:
- RAA(y=0) > RAA(y=1.7)
- Density-induced _enhancement_ mechanism...
- <pT2> flatness

- R. Rapp et al.PRL 92, 212301 (2004)
-  R. Thews et al, Eur. Phys. J C43, 97 (2005)
- Yan, Zhuang, Xu, PRL97, 232301 (2006)
-  Bratkovskaya et al., PRC 69, 054903 (2004)
-  A. Andronic et al., NPA789, 334 (2007)

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## From dA to AA @ RHIC

- RGdC, hep-ph/0701222

- For a given A+A collision at bAA, Glauber provides a set of N+N collisions occurring at bi1 and bi2
- One minimal assumption is rapidity factorization: RAA(|y|,bAA) =
- Σcollisions [RdA(-y,bi1) x RdA(+y,bi2)] / Ncoll
- Works (at least) for absorption & shadowing since production
- 	~ pdf1 x pdf2 x exp –ρσ(L1+L2)

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## What’s going on @SPS ?

- Several models could fit NA50
- Plasma (either thermal or percolative)
- Comovers (hadronic or partonic ?)
- Now NA60...
- Difficult to
- reproduce...

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- Roberta Arnaldi, QM05
- Final in nucl-ex/0706.4361

## “NA50 only” effects @ RHIC

- “NA50 only” effects @ RHIC

- Most of the models that did a good job @ SPS fail @ RHIC
- Gluon dissociation (y~0) doesn’t give the right trend and/or amount of suppression
- Comovers (of unknown partonic/hadronic nature)       give RAA(y=2) > RAA(y=0)
- Parton percolation has an onset at Npart ~ 90 and simultaneous J/ψ + χc + ψ’ melting

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**Notes:**
On pourrait mettre Kotsyuk aussi

## Unaccounted CNM ?

- Strong initial states effect ala color glass condensate ?
- But they have to violate rapidity symmetrisation RAA(|y|) = RdA(-y) x RdA(+y)
- (otherwise taken into account in CNM extrapolation)
- Could this + sequential melting produce RAA(y~0) and RAA(y~1.7) ?
- Double ratio should drop...
- A possibility...

******=0**

******=2**

- This calc. is for
- open charm, but
- similar for J/ ?

- Tuchin, hep-ph/0402298

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## Tuchin & Kharzeev 

- Quarkonia production in cold and hot matters - raphael@in2p3.fr

- Tuchin & Kharzeev

- Hard probes 2004
- _hep-ph/0504133_
- Coherent production of charm (open or closed)
- (y<0 production time to low to make computation)
- Shadowing from CGC computation...

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## Tuchin & Kharzeev...

- Quarkonia production in cold and hot matters - raphael@in2p3.fr

- + absorption for
- SPS & fermilab

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