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Zhangbu Xu （许长补） University of Science & Technology of China

Brookhaven National Laboratory

Heavy-Flavor at RHIC

• Introduction• Open Heavy Quarks• J/y results• Tools to probe Temperature, viscosity

of QCD matter under extreme conditions实验上研究极端条件下 QCD 强场的温度及其流体力学的基本参数

Zhangbu Xu

2Zhangbu Xu

Fundamentals of QCD relevant to our fieldT.D. Lee, 1995

• Quark Confinement• Symmetry Breaking

Gluons carry color-chargeAsymptotic Freedom

3Zhangbu Xu

SU(3) Color Factors

QCD : For SU(3) : Nc = 3 CA = 3, CF = 4/3

CF ~ strength of a gluon coupling to a quarkCA ~ strength of the gluon self coupling TF ~ strength of gluon splitting into a quark pair

CA/CF=9/4

4Zhangbu Xu

Energy Loss and QCD

Experimentally observable (of Eloss) related to basic ingredientof QCD - Gauge Group through Color FactorsOr extracting an effective Color Factor

R. Baier et al., NPB 483 (1997) 291 M. Gyulassy et al., PRL 85 (2000) 5535 S. Wicks et al, nucl-th/0512076

hardparton

path length L

One mechanism of energy loss : Medium induced gluon radiation Eg

Eq

~ 9/42 L<q>

CE sa ^ C

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Consequence of CA/CF=9/4 in A+A

Other models: S. Wicks, I. Vitev, QM08

WHDG, arXiv:nucl-th/0512076

Energy loss

STAR Preliminary

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STAR Preliminary

• Heavy quark suppression ~= light flavor

• Bottom suppression ~=charm suppression

PRL97,98

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Fragmentation Functions

• Will these ingredients be sufficient for p+p collisions?

• How will p+p collisions provide additional information for our understanding of QCD and for model developments

• What will be modified in A+A collisions1. FF 2. Running of aS3. Effective Color Charge factor

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Jet Chemistry in p+p

pT>5 GeV/c 4<pT<5 GeV/c

Zhangbu Xu, QM08, Jaipur, India 9

Extract effective Color FactorsALEPH : ZPC 76 (1997) 1OPAL :EJPC 20 (2001) 601

SU(3) is the gauge group for QCD

aS = 0.119

Heavy Quark Energy loss and thermalization

Deadcone effect of Energy loss Brownian motion in thermal system

Upper bound on escaping parton p

Heavy object in sQGP with AdS/CFTY.L. Dokshitzer, D. Kharzeev, PLB519(2001)199WHDG, arXiv:nucl-th/0512076

D.E. Kharzeev, arXiv:0806.0358,0809.3000

G. Moore, D. Teaney PRC 71 (2005) 064904;H. Van Hees, R. Rapp PRC 71 (2005) 034907

H. Liu, K. Rajagopal and U.A. Wiedemann PRL 97, 182301(2006)J. Casalderrey-Solana, D. Teaney PRD 74(2006) 085012

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Brownian motion and thermalization

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Brownian motion:

arXiv:0805.0364

Hadronic excited states increase interaction cross-sections

Can Energy Loss and Thermalization explain data?

Zhangbu Xu 12

PHENIX: PRL98(2007)172301

New Precise vertex detector upgrades In STAR (HFT) and PHENIX (VTX) precision charm hadron spectra and v2 with improved kinematics.

13Zhangbu Xu

Fundamentals of QCD relevant to our fieldT.D. Lee, 1995

• Quark Confinement• Symmetry Breaking

Gluons carry color-chargeAsymptotic Freedom

Quarkonium in heavy ion collisions

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J/yH. Satz, Nucl. Phys. A (783):249-260(2007)

J/y suppression at low pT could befrom suppressed excited states (y’, cc)F. Karsch, D. Kharzeev and H. Satz, PLB 637, 75 (2006)

High pT direct J/y suppression related to hot wind dissociation?

Hot wind dissociation

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

2-component approachPredicted decrease RAA X. Zhao and R. Rapp, hep-ph/07122407

Color singlet model predicted an increase RAA

(formed outside of medium)K. Farsch and R. Petronzio, PLB 193(1987), 105 J.P. Blaizot and J.Y. Ollitrault, PLB 199(1987),499

T. Gunji, QM08

Zhangbu Xu

Recombination of open charm to J/

Zhangbu Xu 15

c

c

c

c

c

cc c

QGPc+cJ/

G.D. Moore and D. Teaney, Phys. Rev. C 71, 064904(2005); H. van Hees, V. Greco and R. Rapp, Phys. Rev.C 73, 034913 (2006); X. Zhu et al., Phys. Lett. B 647,366 (2007); N. Xu and Z. Xu, Nucl. Phys. A 715, 587c(2003); Z.W. Lin and D. Molnar, Phys. Rev. C 68, 044901(2003); V. Greco, C.M. Ko and R. Rapp, Phys. Lett. B595, 202 (2004); S. Batsouli et al., Phys. Lett. B 557, 26(2003).P. Braun-Munzinger and J. Stachel, Phys. Lett. B 490,196 (2000); A. Andronic et al., Phys. Lett. B 571, 36(2003); L. Grandchamp and R. Rapp, Phys. Lett. B 523,60 (2001); M. I. Gorenstein et al., Phys. Lett. B 524,265 (2002); R.L. Thews, M. Schroedter and J. Rafelski,Phys. Rev. C 63, 054905 (2001);M.I. Gorenstein et al.,J. Phys. G 28, 2151 (2002)…

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color screening and quarkonium supression

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

J/y suppression at low pT maybe from excited stats (y’, cc) F. Karsch, D. Kharzeev and H. Satz, PLB 637, 75 (2006); B. Alessandro et al. (NA50), Eur. Phys. J. C 39 (2005) 335; R. Arnaldi et al. (NA60), Quark Matter 2005; PHENIX: Phys.Rev.Lett.98, 232301,2007.

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

60% direct J/psi

Nu Xu QM09

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Production Mechanism from J/ spectra in p+p Model comparisons:

Color singlet model: direct NNLO still miss the high pT part. P. Artoisenet et al., Phys. Rev. Lett. 101, 152001 (2008), and J.P. Lansberg private communication.

LO CS+CO: better agreement with the measurements, leave little room for higher charmonium states and B feeddown contribution. G. C. Nayak, M. X. Liu, and F. Cooper, Phys. Rev. D68, 034003 (2003), and private communication.

CS and LO CS+CO have different power parameters different diagram contribution?

power parameter: n=8 for NNLO CS n=6 for LO CS+CO

STAR Preliminary

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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 = 1.1 ± 0.3 ± 0.2

• Indicates RAA increase from low pT to high pT • Contrast to AdS/CFT+ Hydro prediction

Jet quenching: strong open charm suppression. A. Adil and I. Vitev, Phys. Lett. B649, 139 (2007), and I. Vitev private communication; S. Wicks et al., Nucl. Phys. A784, 426 (2007), and W. A. Horowitz private communication.

• Formed out of medium? Karsh, Liu, Zhuang, RappAffect by heavy quark/gluon energy loss

• Decay from other particles?

STAR Preliminary

J/y-hadron correlation

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(S+B)/B: 54/14

5.4s

Heavy quark fragmentation

Near side correlationBottom decay or fragmentation

Good S/B ratio makes this measurement possible

J/y-hadron correlation in p+p

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h-h correlation• No significant near side J/y-hadron

azimuthal angle correlation• Constrain B meson’s contribution to

J/y yield• Hints of CSM?

J/ Observations

p+p collisions• Low-pT deviates from xT scaling

soft process dominant • J/-h correlation:

near-side weak away-side same as light quarks diagram: q+gJ/+jet

• d+Au: large cold nuclear effect at low pT

A+A collisions• Low-pT suppression

cold nuclear effect +feeddown (excited states)+ Coalescence

• High-pT RCuCu ~=1Formation timeAdS/CFT (hot wind)Color SingletCu system size too small

21Zhangbu XuZebo Tang’s afternoon talk

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A novel and compact muon telescope detector for QCDLab

A large area of muon telescope detector (MTD) at mid-rapidity, allows for the detection of

• di-muon pairs from QGP thermal radiation, quarkonia, light vector mesons, possible correlations of quarks and gluons as resonances in QGP, and Drell-Yan production • single muons from their semi- leptonic decays of heavy flavor hadrons• advantages over electrons: no conversion, much less Dalitz decay contribution, less affected by radiative losses in the detector materials

+-

BNL LDRD 07—007 project

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J/ Efficiency

MTD: Large acceptance, effective Trigger

dE/dx after TOF cut

What can we do next?

TOF/MTD (Made in China)

Lepton Identification (Created by Chinese)

Quarkonia (J/Psi, Upsilon)

Elliptic flow and RAA

QGP temperature, screening length, AdS/CFT实验上研究极端条件下 QCD 强场的温度及其流体力学的基

本参数

CSR

TOF/STAR/RHIC

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xT scaling in p+p collisionsn is related to thenumber of point-

likeconstituents takingan active role in

theinteraction

n=8: diquark scattering

n=4: QED-like scattering

xT scaling: 1. and proton at pT>2 GeV/c: n=6.6±0.1 PLB 637, 161(2006)2. J/y at high pT: n=5.6±0.2 (the power parameter close to

CS+CO prediction)3. Soft processes affect low pT J/y production

pT>2 GeV/c

STAR Preliminary

Cosmic Ray Results: Long-Strip Multi-gap Resistive Plate Chamber Technology

Long MRPC Technology with double-end readout

HV: 6.3 KVgas mixture: 95% Freon + 5% isobutane

time resolution: ~60 psspatial resolution: ~1cm

efficiency: >95%950 mm

256

mm 25 m

m

Y. Sun et al., nucl-ex/0805.2459

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Compared to Simulation

from data: pT>2 GeV/c, s(z) of muon: ~10 cm

from simulation: pT=2.5 GeV/c, s(z) of muon: ~9 cm

Data and simulation show consistent results

p T (G

eV/c

)

z (cm)

muons pions muons

Lijuan Ruan 2809/27/2008

A prototype muon telescope (MTD) at STAR in d+Au collisions

• MTD hits: matched with real high pT tracks

• z distribution has two components: narrow (muon) and broad (hadron) ones

• Sample luminosity: 4.19 pb-1• In the process of decomposing the

contributions using velocity, dE/dx, tracking topology, EMC

physics results in next few months!!!

Physics (open heavy-flavor):

• Single muon spectrum • e+ mass spectrum

first ever to directly measure irreducible charm dilepton background

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A complete MTD at STARMRPC ToF barrelReady for run 10

RPSD

PMD

FPDFMS

EMC barrel

EMC End Cap

DAQ1000Ready for run 9 FGT

Complete

Ongoing

MTD

R&DHFT

TPC• To install another tray with TOF electronics in run9• Collaborators for a proposal of full scale detector:

56.6% in azimuth, |eta|<0.88; current tray design: 360 modules, 2160 read-out strips, 4320 channels. (TOF: 23 K readout channels).

Golden Age for physics of QCD matter in Heavy-Ion

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“The World, long divided, must unite; long united, must divide. Thus it has ever been.“ ("天下大势，分久必和，和久必分“ ) -- 三国演义

c

c

c

c

c

cc c

QGPc+cJ/

206BC – 220AD 265—420AD

LHCRHIC, FAIR

ALICESTAR, PHENIX

ALICEATLAS, CMS

wQGPsQGP, gQGP

LHC HI starts

Luminosity upgrade:

Further luminosity upgrades (pp, low-E)

RHIC-II science by-passing RHIC-II project

Opportunity for up-grade or 1st EIC stage

RHIC, RHIC-II, LHC-HI and EIC science share a common

theme…

EIC = Electron-Ion Collider; eRHIC = BNL realization by adding e beam to RHIC

Steve Vigdor (AGS/RHIC Users Meeting)

CSR FAIR RHICx2