Status and Future Perspective of J/ y Measurement in Heavy Ion Collisions

Status and Future Perspective of J/

Measurement in Heavy Ion Collisions

T. GunjiCenter for Nuclear Study

University of Tokyo

Heavy Ion Café: 2008/6/28 T. Gunji Title 1/42

Introduction Physics Motivation Charmonium and the Medium Results from SPS and RHIC Future Perspective Summary

Heavy Ion Café: 2008/6/28 T. Gunji Outline 2

Outline

Bound system between ccbar.

mc~1.3 GeVHeavy andsmall system. Long lived (compared to LVM [,,] )Can bemeasured viadi-lepton decay.

Heavy Ion Café: 2008/6/28 T. Gunji Introduction 3

J/family (J/, ’, c)

T. Gunji, D-thesis


Feed down from excited states

J/ = direct J/ + feed down from ’ and c

20% ~ 40% from c ~ 10% from ’

S. X. Oda QM2008

Heavy Ion Café: 2008/6/28 T. Gunji Physics Motivation 5

Color Screening

Color Screening

cc

When Quark-Gluon-Plasma is formed, the attraction between ccbar pairs is reduced due to the color screening.

T. Matsui and H. Satz (1986)

This leads to the suppression of quarkonia yield.

Suppression depends ontemperature of the medium and radius of qqbar system.

T. Matsui and H. SatzPLB 178, 416, (1986)

ccbar~ 0.06fm, exp(-2mc/Tc)~10-7


Melting Temperatures

c

J/ c

S. Digal, F. Karsch and H. Satz T/TC 1/r [fm-1]

(1S)

J/(1S)

c(1P)

’(2S)

b’(2P)

’’(3S)

A.Mocsy HP2008

Potential Model & lattice simulations

Tc~270 MeV

J/ may survive up to 2Tc, while c and ’ are melt at 1.1Tc .

Asakawa & Hatsuda, hep-lat/0308034

Aarts et al., hep-lat/0610065

T. Hatsuda QM2006 (hep-ph/0702293)

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

Other results:c may survive up to ~2Tc. [T. Umeda, PRD. 75, 094502 (07)]J/ may be dissolved at ~1.2Tc. [A. Mocsy et al, PRL 99(2007)211602, HP’08]


pT dependence of Screening Leakage effect

high pT J/ can escape the medium. depends on formation time.(medium vs. J/)

Hot-wind scenario Melting temperature dependson relative velocity between J/ and medium.

4/12 )1)(0()( vTvT meltmelt

M.C.Chu and T. MatsuiPRD 37 (1998) 1851

H. Liu et al. hep-ph/0607062

Heavy Ion Collisions Study of QGPJ/ measurement in heavy ion collisions

has been performed at SPS and RHIC.


Experiment at SPS and RHIC

LEP/LHC

SPSPHENIX

NA38/NA50/NA51/NA60 √sNN ~ 17-20 GeV S+U, p+p, p+d, p+Pb, Pb+PB, In+In …….

PHENIX/STAR √sNN = 200 GeV (x10 SPS) p+p, d+Au, Cu+Cu, Au+Au

STAR

All stage of collisions modify the J/ yield.

Heavy Ion Café: 2008/6/28 T. Gunji Charmonium and the Medium 9

Fate of J/ in Heavy Ion Collisions

Hot and densemedium

Nuclearmedium

• Gluon Shadowing• CGC

• Nuclear Absorption• Cronin

•Color screening •Gluon dissociation•Recombination

• Comover• DDbarJ/+h

Initial stage Hadronic Matter

Gluon ShadowingDepletion of Gluon PDF in nuclei

Color Glass CondensateGluon saturation from non-linear gluon interactions for the high density at small xLarger effect for heavier nuclei


Initial State EffectsEskola et al. NPA696 (2001) 729gluons in Pb / gluons in p

x

AntiShadowing

ShadowingSPS : x~0.1RHIC: x~10-2

LHC: x~3x10-4

Nuclear AbsorptionDissociation of J/ or pre-resonance by spectators.

Cronin effectMultiple scattering of partons


Cold Matter Effects

J/ψL

σabs = 4.18 ± 0.35 mb

at SPS

absLe

Recombination of J/ from uncorrelated ccbar pairs

P = Nccbar/Nh, NJ/ = Nccbar2/Nh

Nccbar(Nh) scales with Ncol(Npart). Nccbar grows faster with CMS energyNegligible at SPS. But not at RHIC. Huge at LHC.

Charm production needs to be understood.Two models:

Statistical hadronization (A. Andronic et al.)Formation at phase boundary according to statistical law.

Kinetic formation (R. Rapp et al.)In-medium formation and destruction by thermal gluons.


Recombination

Medium effects on J/ suppressionColor screening : collective effect

ccbar is not bound to form J/Dissociation of J/ by (thermal) gluons

If J/ is formed, energetic gluons (comoving hadrons) could dissociate J/. J/ + g ccbar (+g)

Both depends on:formation time of QGP and J/ (8~0.3fm)field map of T and and its space-time evolutionScreening : melting temperature and decay widthDissociation: cross section (decay width)


Screening and Gluon Dissociation

They are crucial and to be understood in detail to study the J/ suppression and compare to the experimental data.

How it behaves around Tdiss? Screening: Lattice knows?Dissociation: Rely on pQCD?

Cross section of J/+g->cc(g) Reliable in QGP? Reliable for higher states?


Decay width

G. Bhanot NPB 156 (1979) 3916

k[GeV]

J/+g

¼ +g

Gluon dist.(T=0.35 GeV)

X.N.Wang PLB540 (2002) 62

1

03

0'3

)1)/(exp();(

);(

);()(

TkTkf

Tkkfd

Tkfkkvdv

v

Dissref

Dissref

gDissref

Decay width (cross section with gluons) in QGP is most important quantity to study J/ suppression (even for recombination) How much it is understood in detail?

R. Rapp et alhep-ph/0502208

?

0

))((exp)( /// dxTxS JdisJJ

Td

Cold Matter effectsp+A @400/450 GeV (NA50)p+A @400/158 GeV (NA60)

Heavy Ion Café: 2008/6/28 T. Gunji Results from SPS and RHIC 15

Results from SPS

Stronger suppression than the cold matter effects @ Npart>150.

Very preliminary

P. Cortese HP2008

P. Cortese HP2008

P. Cortese HP2008

Suppression at low pT (<2-3 GeV)Cronin effect Leakage effect. No hot-wind effect(?)


pT dependence of Suppression

R. Arnaldi QM2008

L. Ramello QM2005

Dissociation by thermal gluons


J/ suppression at SPS (1/2)

Pb-Pb @ 158 GeV

ET [GeV]

20 40 100

R. Rapp PLB92 (2004) 212301 X.N.Wang PLB540 (2002) 62

NA60 In-In 158 GeVpreliminary

J/ +g ccbar (pQCD)J/ +g ccbar +g

Sequential Suppression (screening)Only ’ and c melt. (~40%)S (J/) = 0.4*S(c, ’)+0.6

Well agreement with data


J/ suppression at SPS (2/2)

J/

’

F. Karsch et al., PLB, 637 (2006) 75

NA50/NA60 (Pb+Pb, In+In)Large v2Difficult to understand

Ncc is low (no recombination)No charm thermalizationDue to anisotropic absorption in QGP/nuclear matter?


v2 of J/ at SPS

NA50

NA60 v 2X.N.Wang PLB540 (2002) 62

HP2008

HP2008

R. Arnaldi QM2008


RAA vs. Npart at RHICdy

dN

coll

dydN

AA pp

AA

NR

|y|<0.35

1.2<|y|<2.2

RAA (1.2<|y|<2.2) < RAA (|y|<0.35) ~ RAA at SPS (0<y<1)

Why? Why?

PRL.98, 232301 (2007)

arXiv:0801.0220

Suppression islow pT J/ (<5GeV).


pT dependence of RAAPRL.98, 232301 (2007)

QM2008

d+Au collisions


Cold Matter Effect in d+Au at RHICBreakup cross section

PRC 77 024912 (2008)

F. Fleuret HP2008

Break up cross section is compatible to SPS.Need more statistics to constraint cold matter effects.

Extrapolate Cold Matter effect to Au+Au.


RAA vs. Cold Matter effect

EKS shadowing model arXiv:0801.0220 J/ suppression starts at:

Npart~200 at mid-rapidity Npart~100 at forward rapidity

RAA(1.2<|y|<2.2) < RAA (|y|<0.35)

RAA(RHIC |y|<0.35) ~ RAA (SPS)

1: Dissociation + Recombinationdissociation should be similar but recombination is larger at mid-y.2: Initial state effect (CGC)Suppression of J/ production at forward-y due to CGC effect.

1: Stronger dissociation at RHIC supplemented by Recombination 2: Sequential melting and Melting J/ at higher temperature

A. Andronic et al.assuming: No survival J/ above Npart>80


Statistical Hadronization NPA 789 (2007) 334, PLB 652 (2007) 259, PLB 659 (2008) 149

thcccth

occ

thoccth

opcdircc N

NI

NINN 2

0

1

)(

)(

2

1

I1/I0

c

input output

Input charm y distributiond/dy=63 b

d/dy=123 b(PHENIX)

R. Rapp et al. L. Yan et al.…..


Kinetic formation

R. Rapp et al. L. Yan et al.

RAA

Npart

J/+gc+c

arXiv:0712.2407 PRL 97 (2006) 232301

How we precisely know decay width of J/ in QGP?

A. Capella et al.SPS: Comover alone with co = 0.65mb

Good for Pb+Pb but Failed for In+InRHIC: inclusion recombination


Comover + Recombination

Number of binary col.Multiplicity in p+pNon-diffractive p+p cross section

Tywoniuk QM08, arXiv:0712.4331

Saturation could suppress forward J/ in Au+AuFirst numerical estimate, work in progress

M. Nardi, D. Kharzeev, E. Levin, K. Tuchin @ QM2008


Effect of Color Glass Condensate

Calculations based on CGC can reproduce y and b dependence of J/ in Au-Au at RHIC.

Some uncertainty in absolute normalization, leaving room for final state suppression.

Hydro + J/ Model


Sequential Melting at RHICT. Gunji et al. Phys. Rev. C 76:051901 (R), 2007

• 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

Survival Prob. In the medium:

Decay Width:

Motion of J/: free streaming

Total Survival Prob.

Free Parameters:(TJ/, T, fFD )

0

))((exp)( /// dxTxS JdisJJ

J/x0

(pT)

0// )( xx JJ

,// )1( SfSfS FDJFDtotJ

• x0(Production point) is distributed according to the spatial Ncol distribution.• pT is distributed according tothe measured J/ distribution.• J/ azimuthal angle, , is flat (0 to 2).

)()1/(),()( /3

/ JcJdis TTTTTTT


Modeling of J/ suppression

Compare survival probability in the medium.


Results )(CNMRRS

AA

AAAA

Onset of J/ suppression at Npart ~ 160. Gradual decrease of SJ/

tot above Npart~160 reflects that the transverse area with T>TJ/increases. Very sensitive to TJ/ and TJ/ is consistent with lattice results.

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

Heavy Ion Café: 2008/6/28 T. Gunji Results from SPS and RHIC

Decay width below TmeltT. Song, Y. Park and S. H. Lee Phys.Lett.B659:621-627,2008. )()1/(),()( /

3/ JcJdis TTTTTTMT

Decay width below TJ/y is very small.

<0.20

31


Other observables SAA vs. pT

v2 vs. pT

Free streaming Hot-wind

Free streaming Hot-wind

Suppression is flat in case of free streaming and stronger for high pT J/ in case of hot-wind.

v2 is small (<1%) in case of free Streaming and larger for higher pT in case of hot-wind (~3% v2).

3%

3%

20-30%0-10% 20-30%0-10%

40-50% 50-60%

20-30%0-10%

40-50%


J/ v2 at RHIC

NA50

D. Krieg et al. arXiv:0806.0736

Need more data!! Challenging to understand bothSPS and RHIC data.

Negative v2 is possible, when J/ is formed via recombination like light hadrons and charm quarks locally equilibrated. Just Mass Ordering!!

Now.

Need to study:Decay width of quarkonia states in QGP (vs. T)Charm production and recombinationInitial state effect such as CGC.’, c, states, v2, pT dist. …

High statistics data from RHIC (d+A, A+A)!!Go to higher energy (temperature). LHC!!

Heavy Ion Café: 2008/6/28 T. Gunji 34

Where we are now? Where we go?

Results from SPS and RHIC

CGC

Dissociation+Recombination

sequential suppression (J/ melt at RHIC)dissociation + recombination (same amount btw. mid and forward)

Decay width?charm production?

No

Yes

Heavy Ion Café: 2008/6/28 T. Gunji Future Perspective 35

RHIC Run8 d+Au collisions

57,030 J/ (~73,000 from all data)

4,369 J/ ee(~6,000 from all data)

59 nb-1

63 nb-1

~30 times larger stat. compared to run3

Expected improvement in constraints of cold matter effect (red) compared to Run3 (blue)

expected accuracy

simulation

PHENIX upgradeNCC, forward VTX (J//’, c at forward)

STAR upgradeForward muon, full EMC+TOF, HFT

Luminosity


RHIC future

max

min

# x100#J/

100,000 J/ and ~250 per year at highest RHIC luminosities

J/ &

M. Leitch WWND2008

Starts its operation from this summer!!


Large Hadron Collider at CERN

3-42> 1T / Tc

2x1047x103103Vf(fm3)

15- 605-103 (GeV/fm3)

1-3103700430dNch/dy

550020017s (GeV)

LHCRHICSPSCentral collisions

2

3 - 6

2008 p+p, s = 0.9/10 TeV2009 p+p, s = 14 TeV, 1032 cm-2s-1

Pb+Pb, sNN = 5.5 TeV, 5×1025 cm-2s-1

2010~ p+p, s = 14 TeV, 1031 cm-2s-1

,s = 5.5 TeV, 1031 cm-2s-1 Pb+Pb, sNN = 5.5 TeV, 1027 cm-2s-1 p+Pb, sNN = 8.8 TeV, 1029 cm-2s-1

Ar+Ar, sNN = 6.3 TeV, 1029 cm-2s-1

K. Shigaki JPS2008

LHC: ~ 30x larger in √sNN w.r.t. RHIC

T ~ 1.5-2 x RHIC ~ 3-6 x RHIC

ALICE

LHC-b

ATLAS

CMS


Impact on Quarkonia measurement

SPSRHICLHC

30

completesuppression

enhancedrecombination

Large production cross sectionx100 RHIC for bottomx10 RHIC for charm

Cleary see J/ enhancementor strong suppression

Bottomonia suppression would melt only at LHC’ Td ~ J/ Td

Small regeneration’ can unravel J/ suppression vs. regeneration

Much smaller x than at RHIC

down to x~10-4 with charm at y=0CGC, PDF …

X1,2 = M/√s ey

K. Itakura QM05


ALICEJ/, ϒee at mid-rapidity•||<0.9•ITS+TPC: p•TPC+TRD: eID

J/, ϒ at forward-rapidity•-42.5

CNS, Tsukuba: TRDHiroshima: PHOS

Wide y and pT coverageALICE: J/ and ϒATLAS and CMS : ϒ


Acceptance

ALICE Physics Performance Report Vol. 2: J. Phys. G 32 1295 (2006)


Physics Performance

Di-electron Mass dist. in Pb+Pb (one year)nPDF+shadowing+HIJING(<dN/dy>~3000)Separations of J/, ’ and ϒ,ϒ’, and ϒ’’.

Di-muon Mass dist. in Pb+Pb (central)central S[103] B[103] S/B S/(S+B)

J/ 130 680 0.20 150

’ 3.7 300 0.01 6.7

(1S) 1.3 0.8 1.7 29

(2S) 0.35 0.54 0.65 12

(3S) 0.20 0.42 0.48 8.1

J/ suppression characterizes the properties of QGP. ButProduction of J/ in heavy ion collisions is complicated.

initial ~ cold matter ~ screening, dissociation, recombination…Feed down from higher states

SPS: sequential melting or gluon dissociation.Conclusion depends on the decay width (step-like vs. pQCD base) preve

nts the firm conclusion (even at RHIC!!). RHIC: “SPS + CGC” or “SPS + Recombination (mid-y)”

Charm production is key for recombination. (especially y dist.)Need to do and future…

precise calculation of the decay width in “QGP” (vs. T).study of initial state effecthigh statistics (charm production, CGC, cold matter, v2, pT dist.)simultaneous study at “RHIC+LHC”. LHC!!

Heavy Ion Café: 2008/6/28 T. Gunji Summary 42

Summary

Backup slides

Production of ccbar pairsmc~1.3 GeV

s(mc)«1. Pertubavative.1/2mc. Process takes place in short time.

Hadronization Color Singlet Model (pQCD)Color Evaporation ModelColor Octet Model (NRQCD)

8 ~ 1/sqrt(2mcQCD)=0.25fm

Still working hard: pT distribution, polarization (CDF, RHIC). feed down, J/-h correlation (RHIC)


Production (in vacuum)

H. D. Sato


pT dist. of J/

Statistical hadronization A. Andronic et al. nucl-th/0611023, Nucl.Phys.A789:334-356,2007

Date post:	14-Jan-2016
Category:	Documents
Upload:	deon
View:	34 times
Download:	0 times

Status and Future Perspective of J/ y Measurement in Heavy Ion Collisions

Documents