Energy scan programs in HIC - University of Wrocławift.uni.wroc.pl/~cpod2016/Rustamov.pdf ·...

Energy scan programs in HIC Anar Rustamov

[email protected]

¤  Onset of Deconfinement Signals ¤  Particle spectra ¤  Azimuthal modulations

¤  Event-by-Event Fluctuations ¤  Critical point ¤  Phase Boundaries ¤  Confronting measured signals with theory

¤  Conclusions

Probing the matter in a wide energy range

A. Rustamov, CPOD 2016, Wroclaw, Poland

~13 m

ToF-L

ToF-R

PSD

ToF-F

MTPC-R

MTPC-L

VTPC-2VTPC-1

Vertex magnets

TargetGAPTPC

Beam

S4 S5

S2S1

BPD-1 BPD-2 BPD-3

V1V1V0THCCEDAR

z

x

y

p

PHENIX (7.7- 62.4 GeV) STAR (7.7- 62.4 GeV) ALICE (few TeV)

NA61/SHINE (5- 17 GeV) HADES (few GeV)

2


SPS RHIC

Energy Scan Programs

•  Onset of deconfinement •  Search for the critical point •  Locating phase boundaries

3

NA49: PRC 70, 034902 (2004) NA61: Predicted based on PRC 73, 044905 (2006)

Nature, 443, 675 (2006) NPA 504, 668 (1989)

A. Rustamov, CPOD 2016, Wroclaw, Poland 4

Azimuthal Modulations Equation of state

Onset of Deconfinement

Azimuthal Modulations


E d

3Nd3!p

= 12π

d2NpTdpTdy

1 + 2ν1 cos φ −ψ RP( ) + 2ν2cos 2 φ −ψ RP( )( )+ ...⎡⎣

⎤⎦

spherical (radial) directed

vn = cos n φ −ψ RP( )( )

probes EoS Spectators deflected from dense reaction zone

probes EoS sensitive to pressure

Asymmetry out vs. in-plane sensitive to EoS

measure of perfect fluid

elliptic

T =TF +m βT2 ,pT <2GeV

1mT

d2ndmTdy

=αe−mTT

5

Radial Flow, and softening of EoS


[GeV]NNs1 210 410

T [M

eV]

200

400

p+pPb+Pb Au+AuSPS(NA61 p+p)WORLD(p+p)AGSSPS(NA49)RHICLHC(ALICE)

+K 0≈y

[GeV]NNs10 210

2 sc

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6Au+Au (E895)Pb+Pb (NA49)Au+Au (BRAHMS)p+p (NA61/SHINE)

-π+π

Transverse softening Longitudinal softening

p ε( ) = cs2ε

Fermi-Landau initial conditions Ideal Hydrodynamic expansion

dndy

= KsNN14

2πσ y2e− y2

2σ y2 σ y

2 = 83

cs2

1− cs4 ln

s2mN

⎛⎝⎜

⎞⎠⎟

L. D. Landau, Izv. Akad. Nauk, 17, 51 (1953) E. V. Shuryak, Yad. Fiz., 16, 395 (1972) M. Bleicher, arXiv:hep-ph/0509314v1

1pT

d2ndpTdy

= 1mT

d2ndmTdy

=αe−mTT

consistent results however: 1. minimum is not well defined 2. similar behavior for p+p!

6

Directed Flow and onset of deconfinement


The observed sign reversal for protons may also arise from baryon stopping (not connected to phase transition)

7

R. J. M. Snellings et al., PRL 84, 13 (200)

PRL, 112, 162301 (2014)

H. Stoecker, NPA 750 (2005)

PRC 68 (2003) 034903

Elliptic Flow and NCQ scaling


Mass ordering at small pt Meson-baryon separation at large pt Is this connected to deconfinement? •  ALICE reports on braking of NCQ

scaling in Pb+Pb at s1/2 = 2.76 TeV

•  UrQMD predicts the scaling without

phase transition!

8

PRC 88, 014902 (2013)

ALICE: JHEP06(2015)190

J.Phys. G32 (2006) 1121-1130

Decoupling of temperatures


Is this related to the softening of EoS?

9

1mT

d2NdmTdy

∼mtI0pT sinh ρ( )

Tkin

⎛

⎝⎜⎜

⎞

⎠⎟⎟K1

mT cosh ρ( )Tkin

⎛

⎝⎜⎜

⎞

⎠⎟⎟, ρ = tanh−1 βT( )

Stat. Model: A. Andronic et al., Nucl.Phys.A834(2010)237

E.Schnedermann, J.Sollfrank and U.Heinz, Phys.Rev.C48(1993)2462

Event-To-Event Fluctuations Critical Point

Freeze-out systematics Trivial Fluctuations


Fluctuations and Correlations


ωN =N 2 − N 2

N

Σ A,B[ ] = B ω A + A ω B − 2 AB − A B( )A + B

Φ A,B[ ] = A BA + B

Σ A,B[ ] −1⎡⎣

⎤⎦

Wounded Nucleon Model: GCE:

Σ A,B[ ]Φ A,B[ ]

depend neither on volume (Nw) nor on its fluctuations

fluctuation measures are acceptance dependent

Compare experimental results in a common acceptance

N ∝Nw

NA49: Phys. Rev. C89 (2014) 054902

11

Enhanced multiplicity fluctuations near the critical point!

N ∝V


Results From NA49/NA61

A.  Rustamov, POS (2013) 005 M. Mackowiak-Pawlowska, POS (2013) 048

p+p results are described by models. Energy dependencies

are driven by conservation laws and resonance decays.

12


New Results From NA49 on fluctuations

Second moments

structures only for

positive chargers

13

First moments

NA49 preliminary

M. Gazdzicki and M. Gorenstein, Acta. Phys. Pol. B30, 2705 (1999)

NA49: PRC77, 024903 (2008)

Fluctuations of net-charges


pT 4 =

1VT3 lnZ V ,T ,

!µ( )

!χ ijkBQS =

∂i+ j+k pT 4

∂ !µBi ∂ !µQ

i ∂ !µSk

baryon number susceptibility diverges near the critical point

consistency between LQCD and HRG model for μ=0

N2 − N 2 = T 3V !χ2

N , N − conserved charge

kT =

V 2T2

N2 !χ2

N

compressibility ~ susceptibility

Cn,q ==??VT 3χn

q

Particle number fluctuations in GCE

experiment theory

C.R. Allton et al., PRD 68, 014507 (2003) 11 !µ = µ

T

Statistical Models


ni =Ni

V= −T

V∂lnZi

CE

∂µ= gi2π 2

p2dpexp Ei − µi( ) T⎡⎣ ⎤⎦ ±10

∞

∫Canonical ensemble for strangeness

Statistical approach works in the energy range spanning by 3 orders of magnitude!

suppression factor =

HADES data

arxiV: 1512.07070

I1 2z( )I0 2z( )

z – sum of single particle partition functions P. Braun-Munzinger, K. Redlich, J. Stachel In *Hwa, R.C. (ed.) et al.: Quark gluon plasma* 491-599 A.R, M. I. Gorenstein RLB731, 302 (2014)

THERMUS V3.0: S. Wheaton, J.Cleymans: Comput.Phys.Commun.180:84-106,2009

Results from STAR


Non-monotonic behavior for third an fourth cumulants! In this connected to the critical point? Can these results be directly compared with HRG and or LQCD results? How to interpret consistencies and/or deviations?

16

PRL 112 32302 (2014) + QM15


Results from PHENIX/STAR

17

PRC93 (2016) 011901(R)

Data matches with the difference of two Negative Binomial densities fitted to the single multiplicity distributions

PRL 112 32302 (2014) + QM15

Consistent with the Skellam Baseline Larger error bars for kσ 2

PHENIX STAR

No direct comparison due to different acceptances

Extraction of freeze-out parameters


Different T/μ values from STAR and PHENIX? Need for more precise measurements. Is it justified to extract parameters in this way?

18

Trivial volume fluctuations Conservation laws Measurements depend on acceptance!

PRC93 (2016) 011901(R)

A. Bazavov et al., Phys. Rev. Lett. 109 (2012) 192302.

J. Cleymans et al., PRC73 (2006) 034905.

M. J. Tannenbaum, arXiv:1604.08550v1

s1/2=27GeV

Trivial (volume) fluctuations

Model of independent particles sources

N = n1 + n2 + ...+ nNs= n Ns

N 2 = n2 Ns + n 2 Ns2 − Ns( )

n n n n

n1 n2 n3 … ns


c2 N( ) = Ns c2 n( )+ n2c2 Ns( )

Volume fluctuation part vanishes for midrapidity net-particles at ALICE energies!

1/2s6 8 10 12 14 16 18

πω

0

0.5

1

1.5

2

2.5

π

> π<

N

0

200

400

600

ω π( ) =ω n( )+ π ω Ns( )

Pb+Pb, 0-3.5% (NA49) π multiplicity

UrQMD, b < 2.8 fm

example of volume fluctuations

A. R. CPOD 2013

c2 n−n( )Skellam

=c2 n−n( )

α N + N( ) =αc2 N −N( )N + N

+1−α =1−α

Finite acceptance for net-baryons


n =α N , n =α N

n2 =α 2 N2 −α 2 N +α N

nn =α 2 NN

0

1.α →1 c2(n−n)→02.α →0c2 n−n( )→1 trivialfluctuations( )3.GCElimitc2 n−n( ) =1

n – accepted baryons N – 4π baryons

•  The strategy: •  Perform fluctuation analysis in larger acceptance (keep dynamical fluctuations) •  Subtract contributions from conservation laws •  Compare to baselines from LQCD and/or HRG model

B n;N ,α( ) = N!

n! N −n( )!αn 1−α( )N−n

α = n N

Recipe for net-proton analysis in ALICE


c2 p− p( )Skellam

First experimental results from ALICE will be released soon!

Proposed comparison procedure:

•  Perform analysis for

•  Calculate acceptance factors based on experimental data

•  Correct the experimental data

•  Compare to LQCD

1

ΔηΔηth

Δη > Δηth

α Δη( ) = p

acc

B4π

1−αc2 p− p( )Skellam

=1−α

α =

npacc

NB4π

Conclusions


•  Around 30 GeV (s1/2 ≈ 7.6 GeV ) a wide variety of experimental measurements show non-monotonic energy dependences

•  Some of these signals can be interpreted without explicit assumption of

phase transition •  Nor clear signals for the critical point are observed so far

•  Problems in understanding E-by-E measurements of conserved charges22 •  How to put acceptance threshold? •  How to correct for conservation laws and volume fluctuations?

•  New results on net-proton, net-kaon and net-pion fluctuations from ALICE will be released soon

Energy scan programs in HIC - University of Wrocławift.uni.wroc.pl/~cpod2016/Rustamov.pdf ·...

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