ismd, paraty, brazil, sep 2 sep 8, 2006 kai schweda 1 d – d correlations as a sensitive probe of...

1 ISMD, Paraty, Brazil, Sep 2 Sep 8, 2006 Kai Schweda

D – D Correlations asa Sensitive Probe of

Light – quark Thermalization

Kai Schweda, University of Heidelberg

A. Dainese, X. Dong, J. Faivre, Y. Lu, H.G. Ritter, L. Ruan,A. Shabetai, P. Sorensen, N. Xu, H. Zhang, Y. Zhang.


Outline

1) Introduction

2) Strange quark flow: partonic collectivity

3) Heavy quark collectivity

4) Summary


Quark Gluon Plasma

Source: Michael Turner, National Geographic (1996)

Quark Gluon Plasma:

(a) Deconfined and

(b) thermalized state of quarks and gluons

Study partonic EOS at RHIC and LHC(?) Probe thermalization using heavy-quarks


Heavy Ion CollisionsHeavy Ion Collisions

PCM & clust. hadronization

NFD

NFD & hadronic TM

PCM & hadronic TM

CYM & LGT

string & hadronic TM

1) Initial condition: 2) System evolves: 3) Bulk freeze-out:

- baryon transfer - parton/hadron expansion - hadronic dof

- ET production - interaction cease

- Partonic dof Tth, <T>

Time

Temperature

Plot: Steffen A. Bass, Duke University

Heavy-Flavor , K, p

Tch = 160-170 MeV Tfo = 100 MeV


1) Compared to 1) Compared to , , KK, and , and p, p, multi-multi-strange particles strange particles , , are found are found at lower <at lower <TT> but higher T ~ T> but higher T ~ Tchch

Collectivity prior to Collectivity prior to hadronization hadronization

2) Sudden single freeze-out*:2) Sudden single freeze-out*: Resonance decays lower TResonance decays lower Tfo fo

for (for (, , KK, , pp)) Collectivity prior to Collectivity prior to hadronizationhadronization

take snapshot at take snapshot at early (partonic?) stageearly (partonic?) stage

Kinetic Freeze-out

Data: STAR, Data: STAR, Nucl. Phys. A715, 129c(2003).*A. Baran, W. Broniowski and W. Florkowski; nucl-th/0305075


Anisotropy Parameter v2

y

x

py

px

coordinate-space-anisotropy momentum-space-anisotropy

y 2 x 2y 2 x 2

v2 cos2 , tan 1(pypx)

Initial/final conditions, EoS, degrees of freedom


v2 in the Low-pT Region

- Minimum bias data! At low pT, model result fits mass hierarchy well!- Details do not work, need more flow in the model !

P. H

uo

vi ne

n, p

r ivate

com

mu

nica

t i on

s, 20

04


v2 of Multi-strange Hadrons

,,and do flow = Strangeness flows

partonic collectivity at RHIC ! * Inconsistencies in current hydro calculations STAR Preliminary, QM05 conference


Collectivity, Deconfinement at RHIC

- v2, spectra of light hadrons and multi-strange hadrons - scaling with the number of constituent quarks

At RHIC, it seems we have:

Partonic Collectivity

Deconfinement

Thermalization ?

PHENIX: PRL91, 182301(03) STAR: PRL92, 052302(04)

S. Voloshin, NPA715, 379(03)Models: Greco et al, PRC68, 034904(03)X. Dong, et al., Phys. Lett. B597, 328(04).….


Quark Masses

X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu, et al., hep-ph/0604178, subm. to PRL.

Symmetry is broken:

EW Higss mass

QCD dynamical mass

In QGP, c- and b-quark stay heavy

c- and b-quark good probe for medium

created at RHIC/LHC

If heavy quarks flow:

frequent interactions among all

quarks

light quarks (u,d,s) likely to be

thermalized


The key point is to determine

Heavy-Flavor CollectivityD0, D, D+

s, +C, J/, …


Non-photonic electron v2

c (b) e + X

Large syst. uncertainties due to large background

charm collective flow at pt < 2GeV/c

v2(e) favors non-zero v2(c) at pT(e)<2 GeV/c.

V. Greco et al.PLB 595(2004)202

B. Zhang et al.nucl-th/0502056


J/Enhancement at RHIC(LHC)

Statistical hadronization

strong centrality dependence

of J\ yield at LHC

Need total charm yields !

Measure D0, D±, c

Probe deconfinement

and thermalization

Calculations: P. Braun Munzinger, K. Redlich, and J. Stachel, nucl-th/0304013.

cc


J/ yield vs Centrality

Statistical Hadronization

Synopsis:

- Complete screening of primordial

J/ψ’s

- J/ψ’s regenerated at chemical

freezout from thermalized c-cbars

Disagrees with STAR

Barely touches PHENIX data

Large uncertainties in total c-cbar

yield

need precise reference

for total charm ![1] A. Andronic et al., Phys.Lett. B571 (2003) 36-44

[3] STAR, Phys. Rev. Lett. 94 (2005) 062301[2] PHENIX, Phys.Rev.Lett. 96 (2006) 032001

STAR Preliminary


Multiply Heavy-flavored Hadrons

F. Becattini, Phys. Rev. Lett. 95, 022301 (2005);P. Braun Munzinger, K. Redlich, and J. Stachel, nucl-th/0304013.

Statistical hadronization

- de-confined heavy-quarks

- equilibrated heavy-quarks

Enhancement up to x1000 !

Measure cc, cc, Bc, (ccc)

Need total charm yields

Probe deconfinement and

thermalization @ LHC

QGP !

Quarks and gluons hadrons

Pb+Pb

ccc / D :

p+p

x1000


D Meson Pair Correlations

Pythia Calcs.: H. Woehri, priv. comm.

Hadronic Transport Model:E.L. Bratkovskaya et al., PRC 71 (2005) 044901.

ccbar pair production: DDbar

pairs are correlated !

Here: correlation

If charm equilibrates

correlations vanish !

Influence of hadronic

scattering (small) ?

c cbar


Pythia Predictions

p +p : Pyhtia predicts

DDbar – correlations

Stronger at larger pT

Back-to-back corr.

Modified in QGP ?

X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu, et al., hep-ph/0604178, subm. to PRL.


c cbar in QGP

Langevin approach

- describe c-quarks in QGP

- a: momentum-space diffusion

- fragment c hadrons

At small pT corr. smear out

At large pT corr. preserved

Heavy-quark resonances

in QGP a: increases !

Correlations vanish

up to pT = 3 GeV !X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu, et al., hep-ph/0604178, subm. to PRL.

RHIC LHC


Hadronic Re-scattering

Hadronic re-scattering can not completely wash out DD-correlations

Frequent partonic re-scattering needed light quark

thermalization !X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu, et al., hep-ph/0604178, subm. to PRL.


Summary

Strange – quarks flow , , and

Deconfinement at RHIC

Heavy – quarks (c, b) are precise probes

Measure D Dbar correlations

Probe (u,d,s)-quark thermalization

Deconfinement + Thermalization = QGP !


STAR @ RHIC / ALICE @ LHC

• e.g.: D0 K + c = 123m

• Measure precisely secondary decay vertex

• Use silicon pixel technology

precise heavy-flavor measurements at RHIC and LHC

!

Heavy Flavor Tracker


Two Different Ways to Probe Bulk

Use high pT as probe Probe the bulk response

Partons lose energy in medium

Response of medium to pressure

Measure nuclear modification factor RAA

Measure elliptic flow v2

Partonic energy lossdE/dx, gluon density

Partonic equation of stateEoS

It’s all about interactions

Interactions collectivity (e.g. flow)

Frequent interactions Thermalization

ismd, paraty, brazil, sep 2 sep 8, 2006 kai schweda 1 d – d correlations as a sensitive probe of...

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