Zebo Tang, 高能核物理导论 1 10/10/2009 唐泽波中国科学技术大学近代物理系相对论重离子碰撞中 J/ 的产生 Introduction J/ production at low p T J/ production

Zebo Tang, 高能核物理导论 110/10/2009

唐泽波中国科学技术大学近代物理系

相对论重离子碰撞中J/的产生

• Introduction

• J/ production at low pT

• J/ production at high pT


Discovery of J/

PRL33, 1404-1406 (1974) PRL33, 1406-1408 (1974)


Features of J/

cc bound state, r~0.4 fmMass=3.097 GeV/c2, Width=93.2 keV/c2


Charmonium production mechanism

NRQCD

Color singlet

Color octet

Color singlet model (CSM), LO

underpredicted CDF data by order of magnitude

Color octet model (COM), LO

good agreement with CDF cross section

disagreement with CDF polarization

LO

Know your reference!LO CSM LO COM

J/ 3S1

J/

CDF measurement: PRL79,572


Charmonium production mechanism

NRQCD

Color singlet

Color octet

Color singlet model (CSM), LO

underpredicted CDF data by order of magnitude

Color octet model (COM), LO

good agreement with CDF cross section

disagreement with CDF polarization

CSM*, NLO

better agreement

NNLO* applicable at pT>5-7 GeV/c

COM*

improvement of polarization,

NLO will come, valid at pT>3 GeV/c

Decay feeddown (CDF):

(2s): 7%-15%, slightly increase with pT

c0,1,2: ~30%, slightly decrease with pT

B: Strong pT dependence

LO

Know your reference!


Low pT spectra in p+p

CSM+s-channel cut works well at intermediate pT


High pT spectra in p+p

Significantly extend previous measurements from 5 to 14 GeV/c

CEM, LO COM describe overall trend, leave little to no room for feeddown

NNLO* CSM, steeper than data

STAR Preliminary


xT scaling

n is related to thenumber of point-likeconstituents takingan active role in theinteraction

n=8: diquark scattering

n=4: QED-like scattering

and proton at pT>2 GeV/c: n=6.6±0.1 (PLB 637, 161(2006))

J/ at high pT: n=5.6±0.2 (close to CS+CO prediction)

Soft processes affect low pT J/ production

pT>2 GeV/c

STAR Preliminary

pT>5 GeV/c


PolarizationCesar Luiz da Silva, QM2009


Feeddown

R(ψ’) =8.6±2.5% PHENIXR(c) <42% (90%C.L.) PHENIX

Susumu X. Oda, QM2008


Disentangle contributions via Correlations

• J/-hadron correlation can also shed light on different source contribution to J/ production

• CSM vs. COM

1)

no near side correlation

2)

strong near side correlation

g g g /J

g g b b hadron

B X /J X

PLB 200, 380(1988) and PLB 256,112(1991)


BJ/

No significant near side correlationB contribution (13 5) %Little room for parton fragmentation

STAR PreliminaryarXiv:0904.0439


Quark Gluon Plasma

Quark Gluon Plasma:

1) Deconfined and

2) Thermalized state of quarks and gluons


Color screening of heavy quarks

J/ dissociation due to color screening Signature of the QGP formation

Ágnes Mócsy, QM2009

T. Matsui and H. Satz, PLB178, 416 (1986) 23 years story


Plasma Thermometer

?

Quarkonium dissociation temperatures – Digal, Karsch, Satz

Ágnes Mócsy, QM2009


J/ suppression in heavy-ion collisions

Peripheral Central

200 AGeV O+U collisions

NA38, PLB220, 471 (1989)


Nuclear absorption

Inelastic J/ scattering (dissociation) on primordial target and projectile nucleons

suppression of J/

Before the formation of QGP

nothing to do with QGP Cold nuclear matter (CNM) effect

A. Sibirtsev, K. Tsushima and A. W. Thomas, PRC63, 044906

C. Gerschel and J. Hufner, PLB 207, 253 (1988)


Description of absorption

Fully explained the J/ suppressionNo screening effect?

C. Gerschel and J. Hufner, Z. Phys. C 56, 171 (1992)


Anomalous J/ suppression

NA50, NPA 610, 404 (1996)


Anomalous J/ suppression

NA50, Eur. Phys. J. C 39, 335 (2005)

A signal of QGP formation within a “threshold-suppression” scenario

J. P. Blaizot and J. Y. Ollitraut, PRL 77, 1703 (1996)


Evidence of deconfinementNA 50, PLB 477,28 (2000)

c direct J/


More CNM effects


Shadowing/anti-shadowing

P. Amaudruz et al., NPB 441, 3 (1995) S. R. Klein and R. Vogt, PRL 91, 142301 (2003)


Cronin effect

• Main features:

• pT2 (and T) linearly increase with L

(mean thickness of nuclear matter)

• Phenomenological description with the expression

LpLp gNppTT 22 )(

with an energy dependent pT2pp and

a common slope:gN= 0.081±0.002 (GeV/c)2/fm

Multi-scattering of the incoming gluon


Hadronic co-mover dissociation

Sergei G. Matinyan and Berndt Muller, PRC 58, 2994 (1998)

S. Gavin, M. Gyulassy and A. Jackson, PLB 207, 257 (1988)R. Vogt, M. Prakash, P. Koch and T. H. Hansson, PLB 207, 263 (1988)

Inelastic J/ scattering (dissociation) on secondary produced hadronic comovers

Suppression of J/ Nothing to do with QGP Another CNM effect


Parton-induce break-up in QGP

The anomalous suppression depends on our understanding of CNM effects


Move to higher energy


J/ suppression at RHIC

• Similar suppression as that at SPS• More suppression at forward rapidity

Global error = 7%Global error = 12%

Scomparin (proc. QM06) : nucl-ex/0703030

GeVsNN 200


CNM constraints from dAu results


CNM constraints from dAu results

Mid-rapidity Forward/backward rapidity


Forward rapidity

high xlow x

Gluon saturation from non-linear gluon interactions for the high density at small x; amplified in a nucleus.

Kharzeev, Levin, Nardi and Tuchin, 2009

Normal CNM descriptions (blue) give similar (or even smaller) suppression at mid vs forward rapidity• but if peaking in “anti-shadowing” region were flat instead (red dashed) then one would get larger suppression for forward rapidity as has been observed in AuAu data

Mike Leitch, WWND 2008


Mid-rapidityWhy the J/ suppression is similar at RHIC as that at SPS?

1) Regeneration2) Sequential suppression


Regeneration

Grandchamp, Rapp, BrownPRL 92, 212301 (2004) nucl-ex/0611020

Regeneration models give enhancement that compensates for screening• larger gluon density at RHIC expected to give stronger suppression than SPS• but larger charm production at RHIC gives larger regeneration• very sensitive to poorly known open-charm cross sections• forward rapidity lower than mid due to smaller open-charm density there• expect inherited flow from open charm• regeneration much stronger at the LHC!Issues:• need to know what happens to C & ’ & measure J/ flow• flat forward/mid RAA seems inconsistent with increasing regeneration & screening for more central collisionsMike Leitch, WWND 2008


J/ elliptic flow

Inherit open charm flow or not? Regeneration?Too early to compare to models, need more statistics


Sequential suppression

H. Satz, Nucl. Phys. A (783):249-260(2007)

J/ suppression at low pT maybe only from excited stats (’, c) F. Karsch, D. Kharzeev and H. Satz, PLB 637, 75 (2006)

60% from direct J/: not suppressed30% c and 10% ’: dissociated

NA50, EPJ39,335NA60, QM05


Move to high pT


Hot-wind dissociation

J/

H. Liu, K. Rajagopal and U.A. WiedemannPRL 98, 182301(2007) and hep-ph/0607062M. Chernicoff, J. A. Garcia, A. Guijosa hep-th/0607089

Possible to observe J/ suppression from directly produced J/ at high pT


Jet energy lossSTAR: PRL98(2007) 192301

Strong suppress, energy lossSimilar magnitude as light hadrons

PHENIX: PRL98(2007)172301

c/be

hardparton

path length L

Quark

Quark


Nuclear modification factor RAA

• Consistent with no suppression at high pT: RAA(pT>5 GeV/c) = 1.4± 0.4±0.2

• All RHIC measurements:

RAA(pT>5 GeV/c) = 1.1 ± 0.3 ± 0.2

• Indicates RAA increase from low pT to high pT

• Contrast to AdS/CFT+ Hydro prediction H. Liu, K. Rajagopal and U.A. Wiedemann PRL 98, 182301(2007), T. Gunji, JPG 35, 104137(2008) • How does production mechanism (CS vs. CO) affect energy loss?• Good jobs:

• transport+hydro: from initial produced instead of regenerated Y.Liu, Zhen Qu, N. Xu and P. Zhuang, arXiv:0901.2757; N. Xu, QM2009 • two-component model: leakage and B feeddown is important R. Rapp, X. Zhao, arXiv:0806.1239 Anti-shadowing?


Upsilon

dAuR 0.98 0.32 (stat.) 0.28 (sys.)

Consistent with Nbin scaling

Cold Nuclear Matter effects

(Shadowing) are not large.

prelim

inary

RAuAu in progress


Summary

J/ is a unique probe of the hot dense matter produced in heavy-ion collisions

Lots of CNM effects need to be considered

On the way to understand the screening better

As well as J/ production mechanism in hadron collisions

Documents

Zebo Tang, 高能核物理导论 1 10/10/2009 唐泽波 中国科学技术大学近代物理系 相对论重离子碰撞中 J/ 的产生 Introduction J/ production at low p T J/ production

Zebo Tang, 高能核物理导论 1 10/10/2009 唐泽波中国科学技术大学近代物理系相对论重离子碰撞中 J/ 的产生 Introduction J/ production at low p T J/ production