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Nu Xu 1/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
Energy Dependence of the High Moments from Transport Model Simulations
Xiaofeng Luo(1), Bedanga Mohanty(2), and Nu Xu(1,3)
(1) College of Physical Science & Technology, Central China Normal University, Wuhan, 430079, China
(2) School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar, 751005, India (3) Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
Nu Xu 2/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
Beam Energy Scan at RHIC
Observations:
(1) Azimuthally HBT 1st order phase transition
(2) Directed flow v1
1st order phase transition
(3) Dynamical correlations partonic vs. hadronic dof
(4) v2 - NCQ scaling partonic vs. hadronic dof
(5) Fluctuations Critical point, correl. length
- http://drupal.star.bnl.gov/STAR/starnotes/public/sn0493
- arXiv:1007.2613
Study QCD Phase Structure - Signals of phase boundary - Signals for critical point
Nu Xu 3/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
2 TE RHIC, SPS, FAIR
3
3 Phase boundaryRHIC, FAIR, NICA
Exploring the QCD Phase Structure
1
1 Tini, TC
LHC, RHIC
2
Par
ton
ic M
atte
r
Had
ron
ic M
atte
r
Nu Xu 4/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
Previous Summary
1) sQGP formed at RHIC/LHC: - Collectivity: NCQ scaling in v2, … - Jet-quenching, Quarkonia, direct photon, …
2)BES-I Program: - Partonic QGP dominant: √sNN > 39 GeV
Hadronic interactions become dominant: √sNN ≤ 11.5 GeV
What is the structure of QCD phase diagram? - phase boundary?
- QCD critical point?
Nu Xu 5/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
Susceptibilities and Moments Thermodynamic function:
224 2
1( / ) ( / ) cosh[( ) / ]i i i i B i S i Qi
pd m T K m T B S Q T
T
The susceptibility:
€
χq(1) =
1
VT 3 δNq
χq(2) =
1
VT 3 δNq( )2 T 2χq
(4 )
χq(2) = κσ 2
χq(3) =
1
VT 3 δNq( )3 Tχq
(3)
χq(2) = Sσ
χq(4 ) =
1
VT 3 δNq( )4
− 3 δNq( )2 2 ⎛
⎝ ⎜
⎞
⎠ ⎟
Thermodynamic function Susceptibility Moments
Model calculations, e.g. LGT, HRG Measurements
€
T n−4χq(n ) =
1
T 4
∂ n
∂ μq /T( )n P
T
TC,μqT
⎛
⎝ ⎜
⎞
⎠ ⎟T /T c, q = B,Q,S
Conserved Quantum Number
Nu Xu 6/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
Higher Moment: Net-charge
STAR Preliminary
1) Preliminary net-charge results: efficiency, decay, … effects under study
2) Higher statistics data needed below 20 GeV
- HRG Model: K. Redlich et al, private communications
STAR: D. McDonald, QM2012
Nu Xu 7/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
STAR net-proton results: 1) All data show deviations below
Poisson beyond statistical and systematic errors in the 0-5% most central collisions for κσ2 and Sσ at all energies.
2) UrQMD model show monotonic behavior
3) Higher statistics needed for collisions at √sNN < 20 GeV
Net-proton Higher Moments
STAR Preliminary
STAR: X.F. Luo, QM2012
Nu Xu 8/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
Open Issues
1) Effects of conservations, in this case, the baryon conservation.
2) Effects of the resonance decays
3) Effects of the kinematic cuts
4) Net-proton vs. net-Baryon
5) Effect of PID …
Transport Model:
1) AMPT: http://arxiv.org/abs/nucl-th/0411110
- partonic mode- hadronic mode
2) UrQMD: http://urqmd.org/
- hadronic mode
- Obey most conservation laws
- Most hadronic observables are consistent with data
- No phase transition, nor critical point in the model calculations
Nu Xu 9/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
URQMD Net-proton
Net-baryon
1) Simulations are done with the same experimental cuts2) For κ*σ2 net-p and net-B behavior similarly:
a) peripheral centrality bins, values are above unityb) at most central collisions, the value below at lower beam energy
Nu Xu 10/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
AMPT (string melt) Net-proton
Net-baryon
1) Simulations are done with the same experimental cuts2) For κ*σ2 net-p and net-B behavior similarly:
a) peripheral centrality bins, values are above unityb) at most central collisions, the value below at lower beam energy
Nu Xu 11/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
Summary and Outlook
1) Transport model results for net-proton are consistent with experimental observations
2) In these simulations, no significant difference between net-p and net-B
3) At lower beam energies, baryon conservation pushes the value of κ*σ2 below unity
Outlook: RHIC BES-II is needed in order to collect sufficient data for collisions at √sNN < 20 GeV
RHIC provides unique opportunities for exploring matter with QCD degrees of freedom!
Nu Xu 12/12 ”DNP“, Newport Beach, California, December 24 - 27, 2012
2 TE RHIC, SPS, FAIR
3
3 Phase boundaryRHIC, FAIR, NICA
Exploring the QCD Phase Structure
1
1 Tini, TC
LHC, RHIC
2
Par
ton
ic M
atte
r
Had
ron
ic M
atte
r RHIC Top EnergyStudy QGP Properties- heavy flavor hadrons- di-leptons- Jets
BES-IIMap the QCD Phase Structure
HI collisions at √sNN ≤ 20 GeV
