# Presentation: 237466

## J/psi production in sqrt(sNN)=200GeV Cu+Cu collisions at mid-rapidity at RHIC-PHENIX 

- Susumu Oda
- CNS, University of Tokyo
- For the PHENIX Collaboration
- 2007/03/25 (Sun)
- JPS meeting at Tokyo Metropolitan University

- 1/12

## Motivation

- 2/12

## The J/ Puzzle

- shadowing
- or coherence

- CGC - less charm
- at forward rapidity

- absorption
- d+Au constraint?

- ~40% feedown
- from C, ’
- (uncertain fraction)

- configuration of
- ccbar state

- Data – SPS, PHENIX,
- STAR, LHC...
- Need high statistical
- & systematic accuracy

- comovers
- more mid-rapidity
- suppression

- lattice &
- dynamical screening
- J/ not destroyed?

- large gluon density
- destroys J/’s

- Sequential screening
- C, ’ 1st, J/ later

- Regeneration & destruction
- less suppression at mid-rapidity
- narrowing of pT & y
- J/ flow

- large charm
- cross section

- Regeneration
- (in medium?)

- Charm
- dE/dx & flow

**The J/******** Puzzle**

- CNM

- Slide from Mike Leitch QM2006

- 3/12

## Experiment

- Vertex, centrality
- BBC, ZDC
- Mid rapidity (|y|<0.35, e+e- pair)
- Tracking
- DC, PC
- PID
- RICH, EMC
- Forward rapidity (1.2<|y|<2.2, +- pair)
- Tracking
- MuTr
- PID
- MuID

- J/ mass : 3.097 GeV/c2
- J/e+e- : BR 5.93 +/- 0.10 %
- J/+- : BR 5.88 +/- 0.10 %

- 4/12

## Run list

| Run | Ions | sNN | Luminosity | Status | J/ (ee + ) |
| --- | --- | --- | --- | --- | --- |
| 1 | Au+Au | 130 GeV | 1 b-1 |  |  |
| 2 | Au+Au | 200 GeV | 24 b-1 | PRC69, 014901 (2004) | 13 + 0  |
|  | p+p | 200 GeV | 0.15 pb-1 | PRL92, 051802 (2004) | 46 + 66  |
| 3 | d+Au | 200 GeV | 2.74 nb-1 | PRL96, 012304 (2006) | 360 + 1660  |
|  | p+p | 200 GeV | 0.35 pb-1 |  | 130 + 450  |
| 4 | Au+Au | 200 GeV | 241 b-1 | Final nucl-ex/0611020 | 1000 + 4500  |
|  | Au+Au | 62.4 GeV | 9.1 b-1 | Analysis |  13 |
|  | p+p | 200 GeV | 324 nb-1 |  |  |
| 5 | Cu+Cu | 200 GeV | 4.8 nb-1 | Coming soon Preliminary | 2300 + 10000  |
|  | Cu+Cu | 62.4 GeV | 190 b-1 | Preliminary | 60 + 200 |
|  | Cu+Cu | 22.5 GeV | 2.7 b-1 |  |  |
|  | p+p | 200 GeV | 3.8 pb-1 | Final hep-ex/0611020 |  1500 + 8000  |
| 6 | p+p | 200 GeV | 10.7 pb-1 |  |  |
|  | p+p | 62.4 GeV | 0.1 pb-1 |  |  |
| 7 | Au+Au | 200 GeV | ~1 nb-1 ?? |  |  |
| 8 | d+Au?
p+p? | 200 GeV?
200 GeV? |  |  |  |

- 5/12

## Cu+Cu analysis is ongoing.

- EMC-RICH (ERT) trigger, one-track trigger
- Unlike sign pair (e+e-) – Like sign pair (e+e+, e-e-)
- Mass 2.9-3.3 GeV/c2

- e+e- pair mass spectrum

- 6/12

## RAA-Npart

- Bar: uncorrelated error
- Bracket : correlated error

- 7/12

## Cold nuclear matter effect

- 0 mb

- 3 mb

- 0 mb

- 3 mb

- R. Vogt CNM calcs.

- deuteron

- gold

- Larger suppression at forward rapidity in Au+Au.
- Why?

****

****

- Tuchin
- J.Phys. G30 (2004) 1167

- CGC?

- Small absorption and small shadowing

- 8/12

## Recombination? 

**initial**

**pQCD**

**thermal**

**direct y=1.7**

**direct**
**y=0**

**in-medium y=0**

**in-medium y=1.7**

- Yan, Zhuang, Xu
- PRL 97 (2006) 232301

- R.L. Thews and M.L. Mangano
- PRC73 (2006) 014904

- There are many recombination models.

- Experimental data is fitted with
- modified Kaplan function.

- 9/12

## Feed down from c, B? A PYTHIA simulation p+p 200GeV

- J/ rapidity distribution
- Black : 86 gg J/g
- Red : 88 gg  1cg  J/wide, will be dissociated
- Green : 89 gg  2cg  J/: wide, will be dissociated
- Magenta : MSEL5 bb-bar  J/: narrow

- Feed down fraction may be rapidity dependent.
- R(c, y=0)/R(c y=1.7) ~ 0.8.

- 10/12

## Feed down from c, ’? 

- T. Gunji et al., hep-ph/0703061

- Direct measurement of c is very interesting.
- An indication of cJ/+ is seen in RUN-5 p+p.
- In heavy ion collisions???
- An indication of ’ee is also seen in RUN-6 p+p.

- 11/12

- Cu+Cu data might be sensitive to T.

- Au+Au

## Summary and Outlook

- PHENIX measured J/di-lepton in p+p, d+Au, Cu+Cu and Au+Au collisions.
- Strong suppression of yield beyond cold nuclear matter effects is observed.
- Cold nuclear matter effect, recombination and sequential dissociation are needed to be understood.
- Cu+Cu data will come soon.

- 12/12

## Buckups

## Recombination Aside

- |Ypair| < 0.35

- 1.2 < |Ypair| < 2.2

- Throw mc=1.5 GeV/c pairs flat in , , and pT
- Assign sigma based on ECM
- Find average cross-section for bins of y and pT between the quarks
**Most recombination in ********y < 0.5 and ********p****T ****< 1 GeV/c**
- Less recombination at forward rapidity

- y

- y

- pT

- pT

- <σ> (mb)

- <σ> (mb)

- OEM calculation

- R. L. Thews, M. L. Mangano Phys.Rev. C73 (2006) 014904

- Slide from Andrew Glenn  QM2006

## J/ production

- Production
- ~ 60% direct production J/
- ~ 30% via c J/ + x
- ~ 10% via ’ J/ + x
- Large deviations between experiments : c feed-down fraction vs sqrt(s)
- Not measured at RHIC energies

- Slide from Andry Rakotozafindrabe 42nd Rencontres de Moriond