o overview selected results from rhic “light quark” jet quenching

Heavy Flavor Physics at RHIC


Matthias Grosse Perdekamp U of Illinois and RIKEN BNL

o Overview o Selected results from RHIC “light quark” jet quenching and elliptic flow

o Energy loss of heavy quarks in media as tool to study nuclear media formed in heavy ion collisions.


Heavy Flavor Physics at RHIC: Overview

s)s,s, ΥJ/ψ c 321(, , open heavy flavor production spectroscopy:

QGP? A-A

Quarkonia as “Thermometer”: color screening depends on T

Matsui and Satz, Phy.Lett. B 178 (1986)416

1) Energy loss in dense and hot nuclear matter

2) Tomography of DHNM 3) Reference data for quarkonia

PDF(A) p/d-A

1) Modification of PDFs in nuclear environment (anti-) shadowing vs new state of matter (color glass condensate)

2) Reference data for initial state in A-A

QCD p-p, d-A, A-A

1) Cross sections vs rapidity and √s 2) Vacuum energy loss vs media

3) Reference data

1) Hadronization mechanism 2) Reference data for quarkonia

Polarized PDFs p-p

)( gxGmeasure formation process?


Polarized pp: ΔG from charm production

Scale dependence reduced at NLO:Scale dependence reduced at NLO:

Double spin asymmetry electron asymmetry for charm production (I. Bojak and M. Stratmann, hep-ph/0112276)

T

eLL

x

A

Tx

LO NLO


Relativistic Heavy Ion Collider

Au + Au collisions at 200 GeV/u p + p collisions up to 500 GeV spin polarized protons (70%) lots of combinations in species and energy

in between

Performance Au + Au p+p

snn 200 GeV 500 GeV

L [cm-2 s -1 ] 2 x 1026 2 x 1032

Cross-section 7 barns 60 mbarn Interaction rates 14 kHz 12 MHz

Design Parameters:

RHIC Capabilities


Delivered 1196 (b)-1 to Phenix [week ago : 1060]

136 (b)-1 last week [best week: 158]

minimumprojection

physics target

maximumprojection

RHIC Running

2 x designLuminosity!


Charm and J/ψ Data from RHIC

Run I, 2001 Au-Au beams at s=130 GeV•Open charm from PHENIX

Run II, 2002 Au-Au beams and p-p at s=200 GeV•Open charm and J/ from PHENIX

Run III, 2003 d-Au, p-p at s=200 GeV •Open charm from PHENIX and STAR, J/ from PHENIX

Run IV, 2004 Au-Au, s=200 GeV•More measurements to come


STAR: Large acceptance TPC+EMC


Au-Au Event in STAR


PHENIX Physics Capabilities

• 2 central arms: electrons, photons, hadrons– charmonium J/, ’ ee

– vector meson ee – high pT

– direct photons– open charm – hadron physics

• 2 muon arms: muons– “onium” J/, ’, – vector meson – open charm

• combined central and muon arms: charm production DD e

• global detectors

forward energy and multiplicity– event characterization

designed to measure rare probes: + high rate capability & granularity+ good mass resolution and particle ID- limited acceptance

Au-Au & p-p spin


Au-Au and d-Au events in the PHENIX Central Arms

Au-Au d-Au


Open charm in pp: Single electrons

PHENIX: three methods to subtract

photonic background STAR: three methods to identify

electrons

p + pd + Au

PHENIX PRELIMINARY

charm cross sections (barely) agree!

NNcc =1.36 ± 0.20 ± 0.39 mb


Consistency between electron data sets

• STAR slightly above PHENIX


Does the PYTHIA “extrapolation” work?PYTHIA tuned to available data (sNN < 63 GeV) prior to RHIC results

PHENIX PRELIMINARY

spectra are harder than PYTHIA extrapolation from low energies Use parametrization for Au-Au reference Use rapidity dependence from PYTHIA to extract cross section

1Phys. Rev. Lett. 88, 192303 (2002)


Reconstruction of D mesons in dAu Collisions

D0+D0

0 < pT < 3 GeV/c, |y| < 1.0

d+Au minbias

= 1.12 ± 0.20 ± 0.37 mb from D data (1.36 ± 0.20 ± 0.39 mb with electrons)

NNcc


15 fm b 0 fm0 Npart 394

Spectators

Participants

For a given b, Glauber model predicts Npart (No. participants)and Nbinary (No. binary collisions)

Collision Geometry -- “Centrality”

0 Nbinary 1200


Experimental Determination of Centrality

ZDC

ZDC BBC

Au Au

BBC

ZDC: zero degree calorimeter

BBC: beam-beam counter


Almond shape overlap region in coordinate space

Selected Results: Elliptic Flow

Origin: spatial anisotropy of the system when created, followed by multiple scattering of particles in the evolving system spatial anisotropy momentum anisotropy

v2: 2nd harmonic Fourier coefficient in azimuthal distribution of particles with respect to the reaction plane

2cos2 vx

y

p

patan

Outgoingparticle


E. Shuryak


Adler et al., nucl-ex/0206006

Large v2

• Hydrodynamic limit exhausted at RHIC for low pT particles.

• Large magnitude of v2 suggests highly viscous “liquid”: strongly interacting nuclear medium has been

formed!

STAR v2 for charged particles


Probing the nuclear medium formed:

Jet Suppression

charm/bottom dynamics

J/ &

direct photonsCONTROL


Light qs and g jets as probe of the medium

hadrons

q

q

hadronsleadingparticle

leading particle

schematic view of jet production

Jets from hard scattered quarks observed via fast leading particles orazimuthal correlations between the leadingparticles

However, before they create jets, the scattered quarks radiate energy (~ GeV/fm) in the colored medium

Decreases their momentum (fewer high pT particles)Eliminates jet partner on other side

Jet QuenchingJet Quenching


Quantify Nuclear Modification of Hadron Spectra

ddpdT

ddpNdpR

TNN

AA

TAA

TAA /

/)(

2

2

<Nbinary>/inelp+p

nucleon-nucleon cross section

1. Compare Au+Au to nucleon-nucleon cross sections2. Compare Au+Au central/peripheral

Nuclear Modification Factor:

If no “effects”: R < 1 in regime of soft physics R = 1 at high-pT where hard scattering dominates Suppression: R < 1 at high-pT

AA

AA

AA

AA

AA

AA


Quantitative Agreement across Experiments

Effect is real…Final or Initial State Effect?


Centrality Dependence Au-Au vs d-Au

• Significantly different and opposite centrality evolution of Au+Au experiment from d+Au control.

• Jet Suppression is clearly a final state effect.

Au + Au Experiment d + Au Control Experiment

Preliminary DataFinal Data


Heavy Quark Energy Loss in Media

1997 Shuryak proposed that charm quarks may suffer a large energy loss

when propagating through a high opacity plasma, leading to large suppression of D mesons. (E. V. Shuryak, Phys. Rev. C 55, 961 (1997)

2001 Dokshitzer and Kharzeev propose the “dead cone” effect: Reduced gluon emission at small angles in media for heavy quarks may lead to enhancement in D meson production.

2003 Djordjevic and Gyulassy: detailed quantitative treatment of heavy quark energy loss in strongly

interacting media. Predict slight suppression: 0.6-0.8!

Y.L. Dokshitzer and D. E. Kharzeev, Phys. Lett. B 519, 199 (2001)

M. Djordjevic and M. Gyulassy, nucl-th/0310076


Radiative heavy quark energy loss from Magdalena Djordjevic at QM 2004

There are three important medium effects that control the radiative energy loss at RHIC

1) Ter-Mikayelian effect (Djordjevic-Gyulassy Phys.Rev.C68:034914,2003)

2) Transition rediation (Zakharov)

3) Energy loss due to the interaction with the medium

1) 2) 3)

Ter-Mikayelian:

QCD analog todielectric effect

in electrodynamics


1/T A

A

1/T A

A

1/T A

A

Centrality dependence in AuAu

No deviations from binary scaling within uncertainties.

Consistent with Djordjevic and Gyulassy: 10 x more data from Run 2004!

1/T A

A

1/T A

A1

/TA

BE

dN/d

p3 [m

b G

eV-2]

1/T

ABE

dN/d

p3 [m

b G

eV-2]

1/T

ABE

dN/d

p3 [m

b G

eV-2]

1/T

ABE

dN/d

p3 [m

b G

eV-2]

1/T

ABE

dN/d

p3 [m

b G

eV-2]

1/T

ABE

dN/d

p3 [m

b G

eV-2]

pp reference pp reference

pp referencepp reference

pp reference


Centrality dependence in dAu

Single electron spectra in dAu are in good

agreement with the proton reference.

PHENIX PRELIMINARY

1/T

ABE

dN/d

p3 [m

b G

eV-2]

PHENIX PRELIMINARYPHENIX PRELIMINARY

PHENIX PRELIMINARYPHENIX PRELIMINARY

1/T A

B1/

T AB

1/T A

B1/

T AB

1/T

ABE

dN/d

p3 [m

b G

eV-2]

1/T

ABE

dN/d

p3 [m

b G

eV-2]

1/T

ABE

dN/d

p3 [m

b G

eV-2]

1/T

ABE

dN/d

p3 [m

b G

eV-2]


Charm flow?PHENIX PRELIMINARY

• is partonic flow realized?

• v2 of non-photonic electrons indicates non-zero charm flow in AuAu collisions

• uncertainties are large

• definite answer: RUN-04 AuAu data sample!


J/: Does colored medium screen cc ?

0-20%most central Ncoll=779



Proton

R.L. Thews, M. Schroedter, J. Rafelski Phys. Rev. C63 054905 (2001): Plasma coalesence modelfor T=400MeV and ycharm=1.0,2.0, 3.0 and 4.0.

L. Grandchamp, R. Rapp Nucl.

Phys. A&09, 415 (2002) and Phys. Lett. B 523, 50 (2001):Nuclear Absorption+ absoption in a high temperature quark gluon plasma

A. Andronic et. Al. Nucl-th/0303036

Statistics limited:Run 2004!


Summary

• The final state produced in central Au-Au collisions at RHIC is dense and opaque and appears to have the properties of a strongly interaction liquid.

• The energy loss of heavy quarks in nuclear media is an important tool to further characterize the nature of the medium produced at RHIC.

• Heavy flavor production will play an important role in studying nucleon structure in d-A and polarized p-p collisions at RHIC. The experimental possibilities will be greatly enhanced by silicon vertex detector upgrades for PHENIX and STAR. We expect a significant qualitative and quantitative advance from run 2004 in understanding the nature of the matter formed in central collisions at RHIC.


PHENIX: J/e+e- and +- from pp

Central and forward rapidity measurements from Central and Muon Arms:

•Rapidity shape consistent with various PDFs•√s dependence consistent with various PDFs with factorization and renormalization scales chosen to match data

Higher statistics needed to constrain PDFs

= 3.99 +/- 0.61(stat) +/- 0.58(sys) +/- 0.40(abs) b(BR*tot = 239 nb)


PHENIX: J/e+e- and +- from pp

•pT shape consistent with COM over our pT range

•Higher statistics needed to constrain models at high pT

•Polarization measurement limited

o overview selected results from rhic “light quark” jet quenching

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