# Presentation: 517934

**J/********’s at RHIC**
**W.A. Zajc**
**Columbia University**
**With thanks to my PHENIX (and other RHIC) colleagues, **
**and special thanks to**
** ****V. Cianciolo, M. Leitch, Hugo Pereira Da Costa, V.N. Tram, W. Xie**
**See especially **_**[Quarkonia](http://home.physics.ucla.edu/calendar/conferences/sqm2006/agenda/talks/2006_03_30/session_3/)**__**[ Production at RHIC](http://home.physics.ucla.edu/calendar/conferences/sqm2006/agenda/talks/2006_03_30/session_3/)**_**, M. Leitch, SQM 2006. **

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## Outline   

**Experiments**
**Yields**
**Ratios**
**Models**
**Future**
**Helmut**

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**Experiments**

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## Charmonium and Beyond in STAR

- STAR Preliminary

**Dielectron Invariant Mass (GeV/c****2****)**

| Signal | RHIC Exp.
(Au+Au) | RHIC I
(>2008) | RHIC II | LHC
ALICE+ |
| --- | --- | --- | --- | --- |
| J/ →e+e
J/ → | PHENIX | 3,300
29,000 | 45,000
395,000 | 9,500
740,000 |
| → e+e- 
 →  | STAR
PHENIX | 830
80 | 11,200
1,040 | 2,600
8,400  |

**J/******** Run4 AuAu**

**Dielectron Invariant Mass (GeV/c****2****)**

- STAR Preliminary

- J. Gonzalez, SQM

- STAR AuAu
- preliminary

- ( Compilation courtesy of M. Leitch, Strange Quark Matter, 2006 )

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## The PHENIX detector

- J/e+e-

- J/************

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## How PHENIX Measures J/ψ’s

- High resolution tracking and momentum measurement from  Drift chamber.

- Good electron identification from Ring Imaging Cherenkov detector (RICH) and Electromagnetic Calorimeter (EMCal).

- High rate capability: powerful level-1 electron trigger

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## How PHENIX Measures J/ψ’s

- Good  momentum resolution and muon identification from ****Trk and ****ID.

- High rate capability: powerful level-1 dimuon trigger

- How PHENIX Measures J/ψ’s

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##       PHENIX Data Sets

-       **PHENIX Data Sets**

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**Notes:**
Run4 Au+Au data processed using offline level2 triggers
Run5 Cu+Cu data processed using online level1and offline level2 triggers
Run3 p+p data are used as reference for RAA calculations
Run3 d+Au gives baseline for comparison to heavier ions

**Yields**

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

**Cross sections vs p****T**** (p+p, d+Au)**

- Fits to                                   used to extract <pT>2

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## 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

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## p+p Reference

**Consistent with trend of world’s data**
**~Consistent with at least one COM (Color Octet Model) calculation**

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

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## Invariant yields vs pT (A+A)

**Invariant yields vs p****T ****(A+A)**

- Cu+Cu (|y|[1.2,2.2])

- Au+Au (|y|[1.2,2.2])

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**Ratios**

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## Focus on some slice of collision:
Assume 3 nucleons struck in A, and 5 in B
Could weight contribution as
Npart   3 + 5  
Ncoll    3 x 5 

Choice driven by underlying physics:
Low pT  large cross sections   yields  ~Npart
Soft, non-perturbative, “wounded nucleons”, ...
High pT  small cross sections  yields~Ncoll
Hard, perturbative, “binary scaling”,  point-like, A*B, ...

J/’s are complicated ...
(This a general theme of what follows)
Will use Ncoll to  form  ratios RdA  and RAA
Will  present  same as functions of both Npart and Ncoll  

**Assume 3 nucleons struck in A, and 5 in B**
**Could weight contribution as**
**N****part****  **** 3 + 5  **
**N****coll  **** **** 3 x 5 **
**Choice driven by underlying physics:**
**Low p****T ******** large cross sections **** ******** yields  ~N****part**
**Soft, non-perturbative, “wounded nucleons”, ...**
**High p****T ******** ****small cross sections**** ******** ****yields~N****coll**
**Hard, perturbative, “binary scaling”,  point-like, A*B, ...**
**J/********’s are complicated ...**
**(This a general theme of what follows)**
**Will use N****coll**** to  *****form*****  ratios R****dA****  and R****AA**
**Will  *****present*****  same as functions of both N****part**** and N****coll****  **

**Basis for Comparison**

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## Cold Nuclear Matter (CNM)

**Modest nuclear effects as a function of rapidity**
**Suppression for****low x****2**** ~0.003     (x****Au****)**
**No suppression for higher x****2**** ~0.02-0.09       **
**Modest agreement with models incorporating shadowing and absorption**

**Vogt, Phys. Rev. C71:054902, 2005**** **
**Kopeliovich, NP A696:669,2001 **

**Low x****2**** ~ 0.003**
**(shadowing region)**

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**Notes:**
[12] K.J. Eskola, V.J. Kolhinen and C.A. Salgado, Eur. Phys. J. C9, 61 (1999).
[13] L. Frankfurt, V. Guzey and M. Strikman, arXiv:hep-ph/0303022.
Phys.Rev.C71:054902,2005 e-Print Archive: hep-ph/0411378 

## Hot Nuclear Matter

**Good agreement between**
**Au+Au (muons, red)**
**Cu+Cu (muons, blue)****in overlap region**
**Central arm data**
**Au+Au (green)****slightly higher(?)****than muon arms**
**Note different ****rapidity intervals**
**Central |y| < 0.35**
**Muons |y| ******** [1.2,2.2]**
**“****Large” suppression****effects in A+A**

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**Notes:**
What normalization for 62 GeV Cu+Cu?

## Large Compared to What?

**“****Large”, of course, with respect to the d+A reference data**
**Comparable to the “large” suppression observed by NA50**
**( Note change of horizontal axis to N****part**** )**

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## But Not Truly “Large”

**That is:****Much smaller suppression effects than expected based on scaling from SPS to RHIC energies **
**Without “new” mechanisms**

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**Models**

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## Modeling “normal” suppression

**Input:**
**“****EKS” ****shadowing**
**Absorption cross-section********abs**
**Output:**
**Only modest****constraints****on value ****of ********abs**
**Improvement****needed as “background” to other mechanisms**

- 0 mb

- 3 mb

**3 mb**

**0 mb**

- R. Vogt CNM calcs.

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## “Normal” Anomalous Suppression

**Grandchamp, Rapp, Brown; **_**[PRL 92, 212301 (2003)](http://arxiv.org/abs/hep-ph/0306077)**_
**In-media dissolution**
**Cappella, Ferreiro;**_**[Eur](http://arxiv.org/abs/hep-ph/0505032)**__**[. Phys. J C42, 419 (2005) ](http://arxiv.org/abs/hep-ph/0505032)**_
**Absorption, shadowing, comovers**
**Digal, Furtunato, Satz; **_**[Eur](http://arxiv.org/abs/hep-ph/0310354)**__**[. Phys. J C32, 547 (2004)](http://arxiv.org/abs/hep-ph/0310354)**_
**Absorption, shadowing, percolation, color screening**

**DFS**

**GRB**

**C-F**

******’****,********c    **

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## “Anomalous” Anomalous Suppression

**That is, ****regeneration.**
**One example:****Grandchamp, Rapp, Brown; **_**[PRL 92, 212301 (2003)](http://arxiv.org/abs/hep-ph/0306077)**_
**In-media dissolution**
**Plus regeneration from ****“off-diagonal”  c-cbar pairs**

- screening

- regeneration

- sum

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## No Suppression  

**GRB – see previous slide**
**Thews- previous slide, next talk**
**Andronic, Braun-Munzinger, Redlich, Stachel; **_**[Phys. ](http://arxiv.org/abs/nucl-th/0303036)**__**[Lett](http://arxiv.org/abs/nucl-th/0303036)**__**[. B571, 36 (2003)](http://arxiv.org/abs/nucl-th/0303036)**_
**Color screening, recombination**
**Bratkovskaya, Kostyuk, Cassing Stoecker; **_**[Phys. Rev. C69, 054903 (2004)](http://arxiv.org/abs/nucl-th/0402042)**_
**Hadron-string dynamics**
**Kostyuk, Gorenstein, Stoecker, Greiner;**_**[Phys. Rev. C68, 041902 (2003)](http://arxiv.org/abs/hep-ph/0305277)**_
**Color screening, recombination**
**Zhu, Zhuang, Xu;**_**[Phys. ](http://arxiv.org/abs/nucl-th/0411093)**__**[Lett](http://arxiv.org/abs/nucl-th/0411093)**__**[. B607, 107 (2005)](http://arxiv.org/abs/nucl-th/0411093)**_
**Co-movers, gluon break-up, no regeneration**

**               ****of Models...**

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## There Is So Much More To The Story

**(A Sampling)**
**< p****T ****2 ****>  behavior**
**Open charm yields**_**[Phys. Rev. Lett. 94, 082301 (2005).](http://arxiv.org/abs/nucl-ex/0409028)**_
**Open charm distributions**
**Charm energy loss**_**[Phys. Rev. Lett. 96, 032301 (2006). ](http://arxiv.org/abs/nucl-ex/0510047)**_
**Charm flow**_**[Phys. Rev. C72, 024901 (2005)](http://arxiv.org/abs/nucl-ex/0502009)**_

**PHENIX ****Preliminary**

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## Not  Suppressing the J/

**Karsch, Kharzeev, ****Satz; **_**[hep-ph/0512239](http://arxiv.org/abs/hep-ph/0512239)**__**[ ](http://arxiv.org/abs/hep-ph/0512239)**_**:**
**Based on ****LQCD ****results****suggesting****T****J/******** ~ 2 TC**
**Suppression****(only) of ******** ’  and ********C**
**See talk(s) ****to follow**

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**Future**

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## Run-6 (as of today)

**200 GeV polarized p+p collisions**
**Results from ~ real-time production of Level-2 triggers**
**Already ****equals or ****exceeds ****all of  Run-5**
**Expect ****~ 3x this by****end of ****proton ****running****(~ 10 pb****-1**** ) **

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## Hitting Bottom

**Hitting Bottom**

**From Run-5 p+p: ~ 3 pb****-1**
**Current Run-6 :    ~4 pb****-1**

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## Future: Nose Cone Calorimeter

**Replace central arm magnet nosecones (Cu) w/ tungsten-silicon calorimeters**
**Coverage at forward/backward rapidity: 0.9 < |****η****| < 3.5**
******/********0 ****separation for *****p******T***** < 30 GeV/c **
**Jet identification**
****** ****identification gives ****good acceptance**** for ********c ******** J/******** +**** ******

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##    RHIC-II - Heavy Flavor Yields

**All numbers are first rough estimates **
**(including trigger and reconstruction efficiencies) **
**for 12 weeks Au+Au run  (∫L****eff**** dt ~ 18 nb****-1****)**

| Signal | RHIC Exp. | Obtained | RHIC I (>2008) | RHIC II | LHC/ALICE+ |
| --- | --- | --- | --- | --- | --- |
| J/ →e+e
J/ → | PHENIX |   ~800
~7000 | 3,300
29,000 | 45,000
395,000 | 9,500
740,000 |
|  → e+e- 
 →  | STAR
PHENIX | -
- | 830
80 | 11,200
1,040 | 2,600
8,400  |
| B→J/→e+e  
B→J/→ 	 | PHENIX | -
- | 40
420 | 570
5,700 | N/A
N/A |
| c→e+e
c→+ 	 | PHENIX | -
- | 220
8,600 | 2,900* 
117,000* | N/A
N/A |
| D→K | STAR | ~0.4×106 (S/B~1/600) | 30,000**       	 | 30,000**
 | 8000 |

- *  Large backgrounds, quality uncertain as yet
- ** Running at 100 Hz min bias
- +  1 month (= year), P. Crochet, EPJdirect A1, a (2005) and private comm.

- T. Frawley, PANIC’05, RHIC-II Satellite Meeting

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**Notes:**
Alice optimistic

**Helmut**

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## Before Matsui-Satz

**First “m****T**** scaling” plot ?**

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## My First Helmut Sighting

***Deconfinement in Dense Matter*****, by H. Satz**
**Abstract:**
**We survey recent developments in the study of strongly interacting matter by means of quantum chromodynamics on the lattice. The Monte Carlo evaluation of SU(2) Yang-Mills systems is shown to provide a unified thermodynamic description from the hadronic region through the deconfinement transition to a non-interacting gluon gas. We ... discuss possible signals for the formation of a quark-gluon plasma in relativistic heavy ion collisions.  **

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## A Furtive Note-Taker...

**A Furtive Note-Taker...**

**My notes****from Helmut’s ****1981 talk**

**Helmut’s ****1981 talk**

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## 1981 In Context

**State of the art in graphics:**
**State of the art in simulations:**

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## The End is the Beginning

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**Thanks Helmut, for the continuing intellectual journey !**

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**Backup**

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## Test of Npart scaling

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## RAAvs rapidity

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## RAAvs rapidity

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## J/  production in d+Au vs centrality

**J/********  production in d+Au vs centrality**

**Small centrality dependence**
**Models with absorption + shadowing**
** ****shadowing EKS98**
** ****σ****abs**** = 0 to 3 mb **
**σ****abs**** = 1 mb good agreement**
**σ****abs**** = 3 mb is an upper limit**

- Weak shadowing and weak nuclear absorption observed

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