nu xu1/28the phase diagram of qcd, december 13 – 14, 2010, tifr, mumbai, india icpaqgp 2010, goa,...

Nu Xu 1/28The Phase Diagram of QCD, December 13 – 14, 2010, TIFR, Mumbai, India

ICPAQGP 2010, Goa, India

High-Energy Nuclear Collisions and QCD Phase Structure

Nu Xu

(1) Nuclear Science Division, Lawrence Berkeley National Laboratory, USA

(2) College of Physical Science & Technology, Center China Normal University, China


Outline

(1) Introduction: Phase Structure of QCD

(2) RHIC beam energy scan: v2, χp

(3) Phase diagrams of QCD: a collection


Quantum ChromoDynamics

1) QCD is the basic theory for strong interaction. Its degrees of freedom, are well defined at small distance.

2) Little is known regarding the dynamical structures of matter that made from q, g. E.g. the confinement, nucleon spin, the QCD phase structure... Large αS and strong coupling – QCD at long distance.

S

L

Beam Energy Scans at RHIC and LHC

LHC: 2.76 – 5.4 TeV (Pb) (0.9 – 14 TeV (p))

RHIC: 200 – 5 GeV (Au)

FAiR*/NICA: 11 – 4 GeV (Au)

T: 180 – 55 MeV μB: 5 – 800 MeV

(tri-)Critical point

Chemical freeze-out

(2) RHIC Beam Energy Scan


STAR’s BES Plan*√sNN

(GeV) B(Me

V)Events taken (Million MB

events)

5.0 550 5 (?) Run11

7.7 410 5 Run10

11.5 300 7.5 Run10

18 230 100 Run11

27 151 150 Run11

39 112 250 Run10

1) As low the beam energy as possible in order to cover a wide range.2) Marches to corresponding SPS center of mass energy.3) Started in Run10 when the new TOF was ready.

* Phase-I. Depends on the out comes, we may have Phase-II BES at more focused region of the beam energy scan


STAR Detector

MRPC ToF Barrel

BBC

PMD

EMC Barrel

TPC

HLT

Fast DAQ and particle identification over 2p in azimuthal angle in a wide rapidity window.

FTPC


Centrality Determinations

1) Mid-y dN/dη collision centrality Npart, εstd, εpart.

2) Understand the initial condition is essential!


Particle Identification

Beam Energy Timing Resolution Remarks

200 (GeV) 85 (ps) At 39 GeV, using a new calibration scheme without information of start time from VPD (Vertex Position Detector), 87 ps of timing resolution has been achieved.

62.4 (GeV) 90 (ps)

39 (GeV) 85 (ps)

11.5 & 7.7 (GeV) ~ 80 (ps)

√sNN = 39 GeV Au + Au Collisions

TPC TPC+ToF

PID: 7.7, 39, 200 GeV (π±, K±, p)Au+Au at 7.7 GeV Au+Au at 39 GeV Au+Au at 200 GeV


High Moments: Critical Point Search

Measure conserved quantities, B, s, and Q. First: High order fluctuation results consistent with thermalization. First: Tests the long distance QCD predictions in hot/dense medium.

Caveats: (a) static vs. dynamic; (b) net-B vs. net-p; (c) potential effects of freeze-out… R. Gavai, S. Gupta, 1001. 3796 / F. Karsch, K. Redlich, 1007.2581 / M. Stephanov, 0911.1772. STAR: PRL105, 02232(2010) and references therein.


Partonic Collectivity at RHIC!

Partonic Collectivity at RHIC

STAR: preliminary

Session-7: Shi // arXiv 0907.2265 // PHENIX: nucl-ex/0604011

QM

09: arXiv 0907.2265

Number of Quark Scaling in v2

[STA

R Jena: IC

PA

QG

P10]

v 2/n

q[S

TAR

Shi: IC

PA

QG

P10

] At intermediate pT region,

v2-scaling in nq works for π, K, ρ0, p, ϕ, Λ, Ξ, Ω and light nuclei up to 3He.

Coalescence process for hadronization.

Partonic collectivity and de-confinement.


Observable: Quark Scaling

- m ~ mp ~ 1 GeV- ss not K+K- - h << p,

In the hadronic case:(i) No number of quark scaling (ii) Very small value of v2 !


Results on Anisotropic Flow

1) Stronger collectivity at LHC!2) Initial eccentricity ε is largely uncertain

From Kuma, Mohanty and ShiALICE arXie1011.3914


Energy Dependence: K/p Ratio[Kumar: ICPAQGP2010]

J. Randrup & J. Cleymans,Phys. Rev. C 74 (2006) 047901

N(K+)/N(p+) ratio vs. √sNN may reflect the degree of baryon stopping, due to the associate process: NN NΛK+. Important for strangeness production!

√sNN ~ 8 GeV is the max. of freeze-out baryon density.

√sNN~8 GeV


Other Observables

At each collision energy: 1) Local parity violation: a three particle

correlation measurement

2) HBT as a function of reaction plane

3) Directed flow v1

4) E-by-E N(K)/N(p), N(p)/N(p) ratios

5) E-by-E <pT>, <Nch>

6) High moments for net-charge, p, K, p

(3) Collection of

QCD Phase Diagram


E. Fermi: “Notes on Thermodynamics and Statistics ” (1953)

QCD Phase Diagram (1953)


(1, 2, 5-10)ρ0

QCD Phase Diagram 1983

1983 US Long Range Plan - by Gordon Baym

(1, 2, 5-10)*ρ0

TC~200 MeV


QCD Phase Diagram (2009)

1983 US Long Range Plan - by Gordon Baym

nucl-th: 0907.4489, NPA830,709(09) L. McLerran nucl-th 0911.4806: A. Andronic, D. Blaschke, P. Braun-Munzinger, J. Cleymans, K. Fukushima, L.D. McLerran, H. Oeschler, R.D. Pisarski, K. Redlich, C. Sasaki, H. Satz, and J. Stachel

Systematic experimental measurements (Ebeam, A) :

Extract numbers that is related to the QCD phase diagram!


Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006

Slope Parameter Systematics

€

mT = pT2 +m 2

f ∝ exp(−mT /Tslope )

Partonic

Hadronic


Direct Radiation Measurements

Expanding partonic matter at RHIC and LHC!

Di-leptons allow us to measure the direct radiation from the matter with partonic degrees of freedom, no hadronization!

- Low mass region: , , e-e+

minv e-e+

medium effect Chiral symmetry(?)

- Intermediate region: J/ e-e+

minv e-e+

Direct radiation hadronic partonic

STAR already started its di-electron measurements!

Direct radiation:

Hadronic Partonic


Di-lepton Program at STAR

STAR Preliminary

pT (GeV/c)

ωϕ

J/ψ

Key measurements: yields, mass, RAA, v2 thermalization, thermal rates


γ*γ* Interferometry (HBT)[Mohanty: ICAPQGP10]

1) Virtual gamma HBT sensitive to, due to the off-shell mass, is sensitive to the duration of the source, hence the collectivity as a function of emission time.

2) The di-leptons sense ‘volume emission’ while hadrons are mostly ‘surface emission’! Leptons: QGP evolution (phase) can be assessed.

P. Mohanty, J. Alam, B. Monhanty, arXiv:1008.1111

Hadronic Partonic


D-lepton Signal for QGP ExpansionHadronic Partonic

1) Di-lepton transverse mass slope parameters reflect the sources. 2) At the intermediate mass region (IMR), partonic phase is dominate, the

slope parameter vary smoothly while dramatic effects are seen at the low mass region (M ≤ 1 GeV).

J. Deng, Q. Wang, NX, PF. Zhuang arXiv:1009.3091


Summary

1) The QCD phase structure long distance QCD. A serious beam energy scan program, for the search of QCD critical point and phase boundary, has just began.

2) Next generation of new experiments with high rate capabilities are important for the study of the QCD phase structure around the phase boundary. NA61 at SPS, CBM at FAiR and MPD at NICA.

3) In order to understand the dynamical evolution from cold nuclear matter to quark gluon plasma in high-energy nuclear collisions, a good understanding of the initial condition is necessary.

CPOD2011, Nov. 7-11, 2011Wuhan, China(Critical Point and Onset of De-confinement)

International Summer School for High-Energy Nuclear Physics*Nov. 1-5, 2011 Wuhan, China*Supported in part by HIC for FAiR

Many Thanks to the Organizers!


Phase Diagram

QED QCD

Phase Diagram: A map shows that, at given degrees of freedom, how matter organize itself under external conditions.

nu xu1/28the phase diagram of qcd, december 13 – 14, 2010, tifr, mumbai, india icpaqgp 2010, goa,...

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