# Presentation: 682584

## Onset of J/ Melting in Quark-Gluon Fluid at RHIC

***Taku Gunji***
**Center for Nuclear Study**
**University of Tokyo**

- Paper: Phys. Rev. C 76:051901 (R), 2007
- Collaboration with:
- H. Hamagaki (CNS, Univ. of Tokyo),
- T. Hatsuda, T. Hirano, Y. Akamatsu (Phys. Dept. Univ. of Tokyo)

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- Quark Matter 2008, Jaipur, India, 2008/2/9

## Outline

- Physics Motivation
- J/ suppression at RHIC
- Hydro+J/ model
- Determination of J/ melting temperature
- J/ suppression in Hot-wind
- Calculation of J/ v2
- Future plan – forward rapidity
- Summary

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## Physics Motivation

- Quark-Gluon-Plasma (QGP)
- New state of QCD matter expected to be created at high temperature (Tc = 160-190MeV).
- Quarkonia suppression in QGP
- Color Debye Screening
- T.Matsui & H. Satz PLB178 416 (1986)
- Suppression depends on
- temperature (density) and
- radius of QQbar system.
- TJ/ : 1.6Tc~2.0Tc
- T, T’ : ~ 1.1Tc
- Serve as the thermometer in QGP.

- 3

- M.Asakawa and T.Hatsuda, PRL. 92, 012001 (2004)
- A. Jakovac  et al. PRD 75, 014506 (2007)
- G.Aarts et al. arXiv:0705.2198 [hep-lat]. (Full QCD)

## J/ Suppression at RHIC

- J/ suppression in A+A Collisions at RHIC

- CNM effects
- Gluons shadowing
- Nuclear absorption
- Evaluated from J/ production
- in d+Au collisions.
- A.Adare et al. (PHENIX) arXiv:0711.3917

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- Au+Au: A. Adare et al. (PHENIX) PRL 98 232301 (2007)
- Cu+Cu: A. Adare et al. (PHENIX) arXiv:0801.0220

- Au+Au
-  (|y|<0.35)

- Au+Au
- (1.2<|y|<2.2)

- Cu+Cu
-  (|y|<0.35)

- Cu+Cu
-  (1.2<|y|<2.2)

- J/ suppression at mid-rapidity
- at RHIC is compatible to
- CNM effects except most central Au+Au collisions.
- Stronger suppression at forward
- rapidity than CNM effects.

## J/ Suppression at RHIC

- Two proposed scenarios:
- Gluon dissociation + recombination
- Dissociation by thermal gluons supplemented by the regeneration of J/ from ccbar coalescence
- R. Rapp et al. [EPJC34, 91 (2005), arXiv:0712.2407],
- L. Yan et al. [PRL97,232301 (2006)], R. Thews [NPA783 301(2007)],
- A.Andronic et al.[nucl-th/0701079], etc
- _Need to take into account charm production and its modification in the medium, which are still unclear at RHIC._
- Sequential Melting of J/
- Absence of the feed down J/ from c and ’ (30-40%) just above Tc and melt of direct produced J/.
- F. Karsch et al., PLB 637 (2006) 75
- Feed down fraction is unclear at RHIC (<~40% 90%CL).
- _This is still in a qualitative level and need to take into account the space-time evolution to study dynamically._

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## Hydro+J/ model

- First attempt for the study of sequential suppression of charmonia at RHIC.
- Incorporate J/, c and ’ into the evolution of matter.
- Evolution of matter : (3+1)-dimentional relativistic hydrodynamics
- T. Hirano and Y. Nara, PRL 91, 082301, (2003)
- T. Hirano and Y. Nara, PRC 69, 034908, (2003)
- T. Hirano and K. Tsuda, PRC 66, 054905, (2002)
- http://tkynt2.phys.s.u-tokyo.ac.jp/~hirano/parevo/parevo.html
- J/, c and ’ : impurity traversing through the matter
- Assume three kinds of interaction inside QGP.
- Free Streaming
- Hot-Wind
- Complete Thermalization

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- T. Gunji et al. Phys. Rev. C 76:051901 (R), 2007

## Modeling of J/ suppression

- Survival Prob. In the medium:
- Decay Width:
- Motion of J/: free streaming
- Total Survival Prob.
- Free Parameters:
- (*T**J/****, T****, f**FD  *)

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** ****x****0**(Production point) is
- distributed according to the
- spatial **N****col** distribution.
** ****p****T**** **is distributed according to
- the measured J/ distribution.
-  J/ azimuthal angle, ******, **
- is flat (0 to 2).

- T. Song, Y. Park and S. H. Lee
- Phys.Lett.B659:621-627,2008.

## Model results

_**Model results**_

- Best Fit @ (TJ/, T, fFD) = (2.00Tc, 1.34Tc, 10%)

- Bar: uncorrelated sys.
- Bracket: correlated sys.

-  Onset of J/ suppression at Npart ~ 160.
- ( Highest T at Npart~160 reaches to 2.0Tc.)
-  Gradual decrease of SJ/tot above Npart~160 reflects transverse area with T>TJ/ increases.
-  TJ/can be determined in a narrow region.

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- Contour map

- 1

- 2

## Decay width below TJ/

_**Decay width below T**__**J/**__****_

- Decay width :

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- T. Song, Y. Park and S. H. Lee
- Phys.Lett.B659:621-627,2008.

-  Suppression pattern
- is similar up to  < 0.2.
- (T=2Tc)<~0.2 GeV

## Hot-wind scenario 

_**Hot-wind scenario **_

- Melting temperature depends on the relative velocity between J/ and fluid.

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- H. Liu, K. Rajagopal and U. A. Wiedemann :
- hep-ph/0607062.

- (TJ/, T, FD) = (2.0Tc, 1.34Tc, 10%)

-  Magnitude of the suppression in hot
- wind is similar to the free streaming case.
-  Gradual decrease above 50 is the effect
- of hot-wind. Next is SAA vs. pT!

**Free streaming   ****Hot-wind**

## pT dependence of SAA 

_**pT dependence of S**__**AA**__** **_

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**Free streaming    ****Hot-wind**

- 20-30%

- 0-10%

- 40-50%

- 50-60%

-  pT dependence of the suppression is greatly different.
-  Suppression is flat in case of free streaming.
-  Suppression is stronger for high pT J/ in case of hot-wind as predicted.
-  Critical pT in hot-wind relates to the achieved temperature in fluid.

- (TJ/, T, FD) = (2.0Tc, 1.34Tc, 10%)

## Calculation of J/ v2

_**Calculation of J/**__****__** v2**_

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**Free streaming   ****Hot-wind**

- (TJ/, T, FD) = (2.0Tc, 1.34Tc, 10%)

- 20-30%

- 0-10%

- 40-50%

- 50-60%

**v2 = 3%**

**v2 = 3%**

-  v2 is small (<1%) in case of free streaming.
-  v2 is larger for higher pT J/ in case of hot-wind (~3% v2).
-  v2 increases above critical pT.

## Thermalization Scenario

_**Thermalization Scenario**_

- Assume that J/ flows in the fluid (T>Tfo).
- J/ moves according to fluid velocity (T>Tfo) and freeze-out at Tfo. Momentum of J/ is distributed according to Boltzman eq. Then boost J/ according to fluid velocity.

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- 10-20%

- 0-10%

- 20-30%

- 40-50%

**v2 = 30%**

- Tfo = 1.0Tc

-  v2 is much larger than that of free streaming and hot-wind case.
- Large v2 is predicted in low-mid pT since most of J/in low-mid pT are followed by flow of the fluid.
- Magnitude is similar to the case of coalescence model. But tendency is much different for high pT.

**Thermalization**
**Free streaming      **
**Hot-wind**

**v2 = 30%**

## Future plan – forward rapidity 

_**Future plan – forward rapidity **_

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-  Stronger suppression at forward rapidity : CGC? (M. Nardi’s talk Session VI)
-  Further studies will be done in conjunction with CGC.

## Summary

- J/ suppression at RHIC was investigated using hydro+J/ model.
- Dynamical and quantitative approach to the sequential suppression.
- Comparison of the experimental survival probability shows:
- Observed suppression is described well with TJ/~2.0Tc at mid-rapidity and  TJ/ can be determined in a narrow region.
- Decay width seems to be (T=2Tc)<0.2 GeV.
- Hot-wind calculation was done in this model.
- Large suppression and ~3% v2 in high pT region can be seen in a scenario with hot-wind.  High pT J/psi is important for this model.
- Critical pT depends on the achieved temperature in the fluid.
- Thermalization scenario shows :
- larger v2 (10-30%) in low-mid pT region (pT<4 GeV) and small v2 (<5%) in high pT region. Much different from other scenarios.
- Further studies of stronger suppression in forward rapidity will be done in conjunction with CGC. Effect of recombination will be studied.

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## Back Up Slides

## Feeze-out Temp. Dependence

_**Feeze-out Temp. Dependence**_

- Assume that _***“survived”***_ J/ flows in the fluid.
- J/ moves according to fluid (T>Tfo) and freeze-out at Tfo. Momentum of J/ is distributed according to Boltzman eq.

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- 10-20%

- 0-10%

- 20-30%

- 40-50%

**v2 = 30%**

- Tfo = 1.0Tc
- Tfo = 1.1Tc
- Tfo = 1.2Tc

-  Most of low-mid pT J/y is from flowed J/y.
-  Large v2 is predicted
- due to the flow of fluid.
-  It depends on the
- freeze-out temp. of J/y.
-  Magnitude is similar
- in case of coalescence model. But tendency is
- Much different.

## Forward rapidity

_**Forward rapidity**_

- Stronger suppression
- at forward rapidity.
- Gluon saturation (CGC)?
- Leading to suppression
- of charm production

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**Suppression pattern**
**due to CGC**

- K. L. Tuchin hep-ph/0402298

## Forward Rapidity

- (TJ/,T) = (2.02Tc,1.22Tc)
- FD = 30% (y=0),
- FD= (35-50)% (y=2)

_**Forward Rapidity**_

- Experimental SJ/tot (y=2)
- CNM at y=0 & CGC suppression (y=2/y=0)
- Model SJ/tot (y=2)
- Hydro at y=2

-  Need larger feed-down
-   fraction at y=2.
-  Onset of suppression
-   at Npart ~ 240?
-  2.02Tc is achieved
- at Npart~240 at y=2?
- Further analysis is on going.

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- SJ/(y=0)=RAA/CNM(y=0,abs=1mb)

- SJ/(y=2)=RAA/R(CGC)/CNM(y=0,abs=1mb)

## Feed down fraction

_**Feed down fraction**_

- ~40% of J/ from c and ’

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| χ,1,2  J/ | ~30% |
| --- | --- |
|  ́  J/  | 5.5% |

## Complete Thermalization

- T>Tc: J/ moves according to fluid velocity vector.
- T~Tc: J/ freeze-out:
- Re-arrange the J/ px, py and pz using Boltzman Eq (in local fluid coordinate).
- Then boost J/ according to the fluid velocity vector.

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## pT and v2 of flowed J/

- J/ participating in the flow of the matter

- dN/dpT [A.U]

- v2

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## Melting temperature

- Spectral analysis in quenched lattice.

-          **J/******

- c

**J/******

- c

- Datta, Karsch, Petreczky & Wetzorke, hep-lat/0312037

- Asakawa & Hatsuda,
- hep-lat/0308034

**T****c****~270 MeV**

- J/ may survive up to ~2Tc. c and y’ would melt at ~1Tc.

- T. Hatsuda QM2006 (hep-ph/0702293)

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## Melting temperature

_**Melting temperature**_

- Spectral analysis in full lattice (Nf=2).

- T. Hatsuda QM2006 (hep-ph/0702293)

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**J******

******c**

**Aarts et al., hep-lat/0610065**

- Even with the light quarks, J/ may survive up to ~2Tc.

**T****c****~170 MeV**

## Hydro. calculation

_**Hydro. calculation**_

- (3+1) dimensional hydro. (,x,y,s)
- r, T, **v**(vx,vy) at (,x,y,s)
- 0 = 0.6 fm/c, Tc=170 MeV
- Massless parton gas (u,d,s,g)
- Tuned to reproduce dN/dh

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- 

- Hydro data are open to public:
- http://tkynt2.phys.s.u-tokyo.ac.jp/~hirano/parevo/parevo.html

- T.Hirano and Y.Nara, PRL91,082301(2003);
- T.Hirano and Y. Nara PRC69,034908(2004);
- T.Hirano and K.Tsuda, PRC66,054905(2002).

## Hydro+Jet model

- Hydro+“hard probe” works.
- Identified hadron spectrum
- Back-to-back correlation
- Pseudo-y dependence of RAA

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- T. Hirano and Y. Nara  PRL91 082301 (2003)

- T. Hirano and Y. Nara  PRC69 034908 (2004)

- T. Hirano and Y. Nara  PRC68 064902 (2003)

## TJ/ comparison

- This study shows TJ/~2.02Tc.
- Estimation of TJ/ in 3-falvor QCD from quenched lattice QCD.

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**= 1.7**

**= 270/170**

- Asakawa & Hatsuda,
- hep-lat/0308034

- This coincides with the result
- obtained in this study.

## Map of Suppression

- Example of suppression map
- 10-20% centrality, Tmelt = 1.0Tc

- Production
- probability  map

- Temperature Field
-   (=0.6 fm/c)

- Suppression Map
- (integrated over )

- Similar to surface emission!
- Main component of survival J/psi

- Small component
- (gained by large Ncoll )

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## Sensitivity for TJ/& FD

- TJ//Tc = 1.88, 1.94,
-        2.00,  2.06, 2.12

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- TJ/y can be determined
- in a narrow region
- around 2.00Tc.

## Forward-Rapidity

- Use hydro at y=2
- (TJ/y, T, FD) free
- (2.08Tc, 1.62Tc, 70%)
- Chi2 = 0.83
- (TJ/y, T) fixed
- (TJ/y, T) = (2.0, 1.34)
- FD45%, chi2 = 10

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## Hot-wind in hydro+J/ model

- Hot-wind in hydro+J/ model

- T. Gunji, H. Hamagaki, T. Hatsuda, T. Hirano, Y. Akamatsu : Phys. Rev. C 76:051901 (R), 2007
- Parallel talk at QM2008 by T. Gunji , Feb. 9th SessionXVIII 15:20~15:40

- Melting temperatures : (TJ/, T) = (2.0Tc, 1.34Tc)
- 10% feed-down correction

*1: Survival Probability of J/**** vs. N**part** *

- 20-30%
- Npart ~ 170

**H. Liu et al. **
**PRL.98:182301,2007 **

- J/ suppression from Hot-wind scenario was calculated in hydro+J/model.
- Overall suppression pattern is similar in both cases.
- Larger suppression and large v2 (~3%) in the high pT region in a scenario with hot-wind.

*2: Survival Probability of J/**** vs.  pT*

*3: v2 of J/**** vs.  pT*

- Melting temperature in hot-wind