explore the qcd phase diagram - partonic equation of state at rhic
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Nu Xu 1/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Explore the QCD Phase Diagram
- Partonic Equation of State at RHIC
Nu XuLawrence Berkeley National Laboratory
Many Thanks to the Organizers
Nu Xu 2/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Outline
1) Introduction
2) STAR Experimental at RHIC
3) Partonic Collectivity in High-Energy Nuclear Collisions
Nu Xu 3/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
- Identify and study the properties of the matter (EOS) with partonic degrees of freedom.
- Explore the QCD phase diagram.
Physics Goals at RHIC
HydrodynamicFlow Collectivity Local
Thermalization=
Nu Xu 4/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
STAR Experiment
Nu Xu 5/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
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
Polarized spin program - Study proton intrinsic properties
Forward program - Study low-x properties, search for CGC - Study elastic (inelastic) processes (pp2pp) - Investigate gluonic exchanges
Nu Xu 6/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
STAR Detector
MRPC ToF barrelReady for run 10
RPSD
PMD
FPD
FMS
EMC barrel
EMC End Cap
DAQ1000Ready for run 9
Complete
Ongoing
R&D
TPC
FTPC
Full azimuthal particle identification!e, π, ρ, K, K*, p, φ, Λ, Δ, Ξ, Ω, D, ΛC, J/ψ, Υ …
Nu Xu 7/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
HFT
TPC
FGT
STAR Detectors: Full 2π particle identification!
EMC+EEMC+FMS(-1 ≤ ≤ 4)TOF
DAQ1000
Nu Xu 8/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Particle Identification at STAR
STAR TPC
STAR ToF
STAR EMC
STAR HFT
Neutral particles Strange Jets Heavy Quark hyperons Hadrons
e, μ
πK p d
TPC ToF TPC
Log10(p)
Nu Xu 9/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Particle Identification (ii)
Reconstruct particles in full azimuthal acceptance of STAR!
Nu Xu 10/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Hadron Spectra from RHICp+p and Au+Au collisions at 200 GeV
sss
ss
uud
ud
Multi-strange hadron spectra are exponential in their shapes. STAR white papers - Nucl. Phys. A757, 102(2005).€
mT = pT2 +m 2
f ∝ exp(−mT /Tslope )
mor
e ce
ntra
l col
lisio
ns
0-5%
Nu Xu 11/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
- mesons and Strange Baryons
ssbar fusion -meson formation!
STAR: Phys. Lett. B612, 81(2005)
STAR: PRL. 99 (2007) 112301 Phys. Rev. Lett. 98, 62301(2007)
Nu Xu 12/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
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
)2/(
)3/(
)2/(
)3/(
T
T
T
T
p
pd
p
ps
Nu Xu 13/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
STAR Detector
MRPC ToF barrelReady for run 10
RPSD
PMD
FPD
FMS
EMC barrel
EMC End Cap
DAQ1000Ready for run 9 FGT
Complete
Ongoing
MTD
R&DHFT
TPC
Nu Xu 14/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Quark Masses
1) Higgs mass: electro-weak symmetry breaking. (current quark mass)
2) QCD mass: Chiral symmetry breaking. (constituent quark mass)
é New mass scale compared to
the excitation of the system.
é Important tool for studying properties of the hot/dense medium at RHIC.
é Test pQCD predictions at RHIC.Total quark mass (MeV)
Nu Xu 15/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Charm Hadron v2
- 200 GeV Au+Au m.b. collisions (500M events). - Charm hadron collectivity drag/diffusion constants
medium properties!
- 200 GeV Au+Au m.b. collisions (|y|<0.5 500M events)- Charm hadron RAA
energy loss mechanism, e.g. collisional vs. radiative!
Nu Xu 16/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Direct Radiation
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
- High mass region: J/ e-e+
minv e-e+
Direct radiation
PRL (07)
Nu Xu 17/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
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)Û Equation of State (EOS)Û No thermalization is needed – pressure gradient only
depends on the density gradient and interactions. Space-time-momentum correlations!
Nu Xu 18/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
y
x
py
px
coordinate-space-anisotropy momentum-space-anisotropy
Anisotropy Parameter v2
€
ε =⟨y 2 − x 2⟩⟨y 2 + x 2⟩
v2 = cos2ϕ , ϕ = tan−1(py
px
)
Initial/final conditions, EoS, degrees of freedom
Nu Xu 19/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Transverse Flow Observables
1) Radial flow – integrated over whole history of the evolution 2) Directed flow (v1) – relatively early3) Elliptic flow (v2) – relatively early
- Mass dependent: characteristic of hydrodynamic behavior.
€
dr σ
dΩ=
d3σ
dpxdpydpz
=dN
p tdp tdydϕ=
1
2π
dN
p tdp tdy1+ 2v icos(i ϕ )
i=1
∑ ⎡
⎣ ⎢
⎤
⎦ ⎥
p t = p x2 + p y
2 , m t = p t2 + m2
v i = cos(iϕ )event
ϕ = tan−1 py
px
⎛
⎝ ⎜
⎞
⎠ ⎟
Nu Xu 20/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
v2 at Low pT Region
- 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.
P. Huo
vi ne
n, p
r ivate
com
mu
nica
t i on
s, 20
04
Nu Xu 21/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Collectivity, Deconfinement at RHIC - v2 of light hadrons and multi-strange hadrons - scaling by the number of quarks
At RHIC: Nq scaling novel hadronization processê 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/0602025Nonaka et al. PLB583, 73(04)X. Dong, et al., Phys. Lett. B597, 328(04).….
i ii
Nu Xu 22/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
-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
Nu Xu 23/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Centrality Dependence STAR: Phys. Rev. C77, 54901(2008)
200 GeV Au+Au
Larger v2/part indicates stronger flow in more central collisions. NO part scaling. The observed nq-scaling does not necessarily mean thermalization.
S. Voloshin, A. Poskanzer, PL B474, 27(00).D. Teaney, et. al., nucl-th/0110037
Nu Xu 24/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
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– K0 value is determined so as to reproduce the
transport model calculation (K0 = 0.7 ± 0.03)* *C. Gombeaud and J.-Y. Ollitrault, PRC77, 054904 (2008)
σ : partonic cross sectioncs : speed of soundS : transverse area
Nu Xu 25/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Centrality Dependence of v2
• Ideal hydro v2/ε - ε from “optical” Glauber
model
• Simultaneous fits
Note: Fit v2{4} and v2{ZDC-SMD} for charged hadrons not plotted here
PHENIX π, K and p: preliminary, nucl-ex/0604011v1STAR K0
S, Λ, : 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
Nu Xu 26/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
Ideal Hydrodynamic Limit
- Only approaching hydro limit at most central collisions!- Questions:
Viscous effects ?? or Non-thermalization in HI collisions ??
€
v2
ε=
h
1+1.4K
K =λ
R1
K=
σ
S
dN
dy
v2 max Drescher, Dumitru, Gombeaud, J.Ollitrault; Phys. Rev. C76, 024905 (2007)
Nu Xu 27/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
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
Nu Xu 28/28VIII International Workshop on Relativistic Aspects of Nuclear Physics, Rio de Janeiro, Brazil, 3-6, November , 2008
The QCD Critical Point- LGT prediction on the transitiontemperature TC is robust.
- LGT calculation, universality, andmodels hinted the existence ofthe critical point on the QCD phasediagram* at finite baryon chemicalpotential. - Experimental evidence for eitherthe critical point or 1st order transition is important for ourknowledge 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 Scan2011: Heavy Quark measurements