Explore the QCD Phase Diagram
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Explore the QCD Phase Diagram - Partonic Equation of State at RHIC Nu Xu Lawrence Berkeley National Laboratory Many Thanks to the Organizers. Outline. Introduction 2) STAR Experimental at RHIC 3) Partonic Collectivity in High-Energy Nuclear Collisions. Physics Goals at RHIC.

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Explore the qcd phase diagram partonic equation of state at rhic

Explore the QCD Phase Diagram

- Partonic Equation of State at RHIC

Nu XuLawrence Berkeley National Laboratory

Many Thanks to the Organizers


Outline

Outline

  • Introduction

    2) STAR Experimental at RHIC

    3) Partonic Collectivity in High-Energy Nuclear Collisions


Physics goals at rhic

Physics Goals at RHIC

  • Identify and study the properties

  • of the matter (EOS) with partonic

  • degrees of freedom.

  • - Explore the QCD phase diagram.

  • Hydrodynamic

    Flow

    Collectivity

    Local

    Thermalization

    = 


    Star experiment

    STAR Experiment


    Star physics focus

    1) Heavy-ion program

    - Study medium properties, EoS

    - pQCD in hot and dense medium

    2) RHIC beam energy scan

    - Search for critical point

    - Chiral symmetry restoration

    STAR Physics Focus

    Polarized spin program

    - Study proton intrinsic properties

    Forward program

    - Study low-xproperties, search for CGC

    - Study elastic (inelastic) processes (pp2pp)

    - Investigate gluonicexchanges


    Explore the qcd phase diagram partonic equation of state at rhic

    STAR Detector

    EMC barrel

    MRPC ToF barrel

    Ready for run 10

    EMC End Cap

    RPSD

    FMS

    FPD

    TPC

    PMD

    Complete

    Ongoing

    DAQ1000

    Ready for run 9

    FTPC

    R&D

    Full azimuthal particle identification!

    e, π, ρ, K, K*, p, φ, Λ, Δ, Ξ, Ω, D, ΛC, J/ψ, Υ …


    Explore the qcd phase diagram partonic equation of state at rhic

    STAR Detectors: Full 2π particle identification!

    EMC+EEMC+FMS

    (-1 ≤  ≤ 4)

    TPC

    TOF

    DAQ1000

    HFT

    FGT


    Particle identification at star

    Particle Identification at STAR

    TPC ToF TPC

    STAR TPC

    K pd

    π

    e, μ

    STAR ToF

    Log10(p)

    STAR HFT

    STAR EMC

    Neutral particles Strange Jets Heavy Quark

    hyperons Hadrons


    Particle identification ii

    Particle Identification (ii)

    Reconstruct particles in full azimuthal acceptance of STAR!


    Hadron spectra from rhic p p and au au collisions at 200 gev

    ud

    ss

    uud

    sss

    Hadron Spectra from RHICp+p and Au+Au collisions at 200 GeV

    0-5%

    more central collisions

    Multi-strange hadron spectra are exponential in their shapes.

    STAR white papers - Nucl. Phys. A757, 102(2005).


    Mesons and strange baryons

    STAR: PRL. 99(2007)112301 Phys. Rev. Lett. 98, 62301(2007)

    - mesons and Strange Baryons

    ssbar fusion -meson formation!

    STAR: Phys. Lett. B612, 81(2005)


    Explore the qcd phase diagram partonic equation of state at rhic

    The s-and d-quark Spectra

    Assuming that the processes of hadronization follow coalescence

    - parton spectra

    - ‘partonic collective flow’

    velocity ~ 0.35-0.45 c

    JinHui Chen: SQM08

    c.f. Phys. Rev. C78 (2008) 034907


    Explore the qcd phase diagram partonic equation of state at rhic

    STAR Detector

    MTD

    EMC barrel

    MRPC ToF barrel

    Ready for run 10

    EMC End Cap

    RPSD

    FMS

    FPD

    TPC

    PMD

    Complete

    Ongoing

    DAQ1000

    Ready for run 9

    HFT

    FGT

    R&D


    Quark masses

    • Higgs mass: electro-weak symmetry breaking. (current quark mass)

    • QCD mass: Chiral symmetry breaking. (constituent quark mass)

    • New mass scale compared to the excitation of the system.

    • Important tool for studying properties of the hot/dense medium at RHIC.

    • Test pQCD predictions at RHIC.

    Quark Masses

    Total quark mass (MeV)


    Charm hadron v 2

    Charm Hadron v2

    • 200 GeV Au+Aum.b.

    • collisions (500M events).

    • - Charm hadron collectivity 

    • drag/diffusion constants 

    • medium properties!

    • 200 GeV Au+Aum.b.

    • collisions (|y|<0.5 500M events)

    • Charm hadron RAA

    • energy loss mechanism, e.g.

    • collisionalvs. radiative!


    Direct radiation

    PRL (07)

    • 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

    • - High mass region:

    • J/e-e+

    • minve-e+

    • Direct radiation

    Expanding partonic matter at RHIC and LHC!

    Direct Radiation


    Pressure flow

    Pressure, Flow, …

    • tds = dU + pdV

      s– entropy; p – pressure; U – internal energy; V – volume

      t= kBT, thermal energy per dof

    • In high-energy nuclear collisions, interaction among constituents and density distribution will lead to:

    • pressure gradient  collective flow

      number of degrees of freedom (dof)

    • Equation of State (EOS)

    • No thermalization is needed – pressure gradient only depends on thedensity gradient and interactions.

      Space-time-momentum correlations!


    Anisotropy parameter v 2

    Anisotropy Parameter v2

    coordinate-space-anisotropy  momentum-space-anisotropy

    y

    py

    px

    x

    Initial/final conditions, EoS, degrees of freedom


    Transverse flow observables

    Transverse Flow Observables

    1) Radial flow – integrated over whole history of the evolution

    2) Directed flow (v1) – relatively early

    3) Elliptic flow (v2) – relatively early

    - Mass dependent: characteristic of hydrodynamic behavior.


    V 2 at low p t region

    v2 at Low pT Region

    P. Huovinen, private communications, 2004

    • Minimum bias data!

    • At low pT, model result fits mass hierarchy well - Collective motion at RHIC

    • - More work needed to fix the details in the model calculations.


    Collectivity deconfinement at rhic

    Collectivity, Deconfinement at RHIC

    - v2 of light hadrons and

    multi-strange hadrons

    - scaling by the number

    of quarks

    At RHIC:

    Nqscaling

    novel hadronization

    process

    • Parton flow

    • De-confinement

    • PHENIX: PRL91, 182301(03)

    • STAR: PRL92, 052302(04), 95, 122301(05)

    • nucl-ex/0405022, QM05

    • S. Voloshin, NPA715, 379(03)

    • Models: Greco et al, PRC68, 034904(03)

    • Chen, Ko, nucl-th/0602025

    • Nonaka et al. PLB583, 73(04)

    • X. Dong, et al., Phys. Lett. B597, 328(04).

    • ….

    i ii


    Meson flow partonic flow

     -meson Flow: Partonic Flow

    “-mesons are produced via coalescence of seemingly thermalized quarks in central Au+Au collisions. This observation implies hot and dense matter with partonic collectivity has been formed at RHIC”

    STAR: Phys. Rev. Lett. 99 (2007) 112301// * STAR, Duke, TAMU

    ** OZI rule


    Centrality dependence

    Centrality Dependence

    STAR: Phys. Rev. C77, 54901(2008)

    200 GeV Au+Au

    S. Voloshin, A. Poskanzer, PL B474, 27(00).

    D. Teaney, et. al., nucl-th/0110037

    • Larger v2/part indicates stronger flow in more central collisions.

    • NO partscaling.

    • The observed nq-scaling does not necessarily mean thermalization.


    Knudsen fit

    Assuming that σ is same for all hadrons

    Note: only extract the product K0σcs

    K0 = 0.7 and cs2 = 1/3 (fixed)

    S is estimated from Glauber MC simulation

    K0value is determined so as to reproduce the transport model calculation (K0 = 0.7 ± 0.03)*

    *C. Gombeaud and J.-Y. Ollitrault, PRC77, 054904 (2008)

    Knudsen Fit

    σ : partonic cross section

    cs : speed of sound

    S : transverse area


    Centrality dependence of v 2

    Ideal hydro v2/ε

    - εfrom“optical”Glaubermodel

    Simultaneous fits

    Note: Fit v2{4} and v2{ZDC-SMD} for charged hadrons not plotted here

    PHENIX π, K and p: preliminary, nucl-ex/0604011v1

    STAR K0S, Λ, Ξ : Phys. Rev. C77, 054901 (2008)

    STAR φ : Phys. Rev. Lett. 99, 112301 (2007)

    Ideal Hydro. : P. Huovinen and P. V. Ruuskanen,

    Annu. Rev. Nucl. Part. Sci. 56, 163 (2006) and private communication

    Centrality Dependence of 〈v2〉


    Ideal hydrodynamic limit

    Ideal Hydrodynamic Limit

    Drescher, Dumitru, Gombeaud, J.Ollitrault;

    Phys. Rev. C76, 024905 (2007)

    v2 max

    • - Only approaching hydro limit at most central collisions!

    • Questions:

    • Viscous effects ?? or Non-thermalization in HI collisions ??


    Sqgp and the qcd phase diagram

    In 200 GeV Au+Au collisions at RHIC, strongly

    interacting matter formed:

    - Jet energy loss: RAA

    - Strong collectivity: v0, v1, v2

    - Hadronization via coalescence: nq-scaling

    Questions:

    Has the thermalization reached at RHIC?

    - Serious analysis with dN/dpT and dv2/dpT results…

    - Heavy quark measurements

    When (at which energy) does this transition happen?

    What does the QCD phase diagram look like?

    -RHIC Beam Energy Scan

    sQGPand the QCD Phase Diagram


    The qcd critical point

    The QCD Critical Point

    - LGT prediction on the transition

    temperature TC is robust.

    - LGT calculation, universality, and

    models hinted the existence of

    the critical point on the QCD phase

    diagram* at finite baryon chemical

    potential.

    - Experimental evidence for either

    the critical point or 1st order

    transition is important for our

    knowledge of the QCD phase

    diagram*.

    * Thermalization has been assumed

    M. Stephanov, K. Rajagopal, and E. Shuryak, PRL 81, 4816(98)

    K. Rajagopal, PR D61, 105017 (00)

    http://www.er.doe.gov/np/nsac/docs/Nuclear-Science.Low-Res.pdf

    2010: RHIC Beam Energy Scan

    2011: Heavy Quark measurements


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