review of structures in the energy dependence of hadronic observables

Review of Structures in the EnergyDependence of Hadronic Observables

Christoph Blume Int. Workshop onCritical Point andOnset of DeconfinementFlorence, July 3-6, 2006

Christoph Blume Florence, July 3-6 2006 2

IntroductionExploring the QCD Phase Diagram

Cross over

Critical point

Lattice calculations:Fodor and KatzBielefeld-Swansea group

Hadron gas fits ():J. Manninen et al.

1st order

Chemical freeze-outpoints approach phaseboundary at SPS energies

Transition to QGP likelyto happen in this regionEbeam = 20 - 158 AGeV (sNN = 6.3 - 17.3 GeV)


IntroductionEnergy Dependence

Any evidence for a phase transition (or the even critical point)in hadronic observables seen ?

Look for “non-smooth” behaviour in the energy dependenciesProminent examples: “horn”, “kink”, “step”

Any other structures?

How significant are they?

Comparison to hadronic modelsTransport models (UrQMD + HSD)

Statistical models

Identify “trivial” structures

Baseline comparison


IntroductionHadronic Scenery at SPS

J. Cleymans, H. Oeschler, K. Redlich, and S. Wheaton, hep-ph/0510283

Transition from baryondominated to mesondominated system

Statistical model: Transition at sNN 8 GeV Maximum of strangeness prod.

Evidences for structures beyond this?


Introduction”Horn” / “Kink” / “Step”

K++

/N

w

HORN KINK STEP


IntroductionExperiments

AGS SPS RHIC

Experiments Ebeam (A GeV) snn (GeV) System Particles

AGSE802, E866, E877, E891, E895, E917

2-10.7 2.7-4.9 Au+Au , K, p,

SPSNA45, NA49, NA57,

(NA44, WA98)20-158 6.3-17.3 Pb+Pb

, K, p, , , , ,...

RHICSTAR, PHENIX,

BRAHMS, PHOBOS- 20.0-200.0 Au+Au

, K, p, , , , , ...


IntroductionObservables

Particle yieldsPionsStrangeness

Transverse mass spectraRadial flow EOS

Elliptic flowInitial pressure

Bose-Einstein correlationsSystem size and lifetime

Not discussed here: Fluctuations


Particle YieldsEnergy Dependence of Particle Ratios

5.1

K+/+

K-/-

/

/

-/

-++/

UrQMD + HSDE.L. Bratkovskaya et al.,PRC 69 (2004), 054907

Statistical hadron gas:P. Braun-Munzinger,J. Cleymans, H. Oeschler, and K. RedlichNucl. Phys. A697 (2002) 902

s = 1

Full chem.equilibriumbaseline


Particle YieldsComparison to Statistical Model

(dat

a –

mod

el)/(

data

)

(dat

a –

mod

el)/(

data

)Statistical hadron gas:P. Braun-Munzinger,J. Cleymans, H. Oeschler, and K. RedlichNucl. Phys. A697 (2002) 902

Kaons and deviate from stat. model for sNN 7-8GeV

?

?Different situationfor hyperons

s = 1


Particle YieldsPosition of Maxima

RatioMaximum

atsNN (GeV)

K+/+ 10.8

/ 5.1

-/+ 10.2

-/+ 27.0

Statistical modelprediction:

J. Cleymans, H. Oeschler, K. Redlich, and S. Wheaton, hep-ph/0510283


Particle YieldsLocal Slope of Energy Dependence: and K

No significant structure for pions

Indications for sudden changes in kaon e.-dependence (?)

iNNiNN

ii

NN ss

NN

s

N

1

1


Particle YieldsComparison s- and s-Carriers

s-quark carriers: K-, K0 (1)

(incl. 0) 0,-, - (2)

± (3)

s-quark carriers: K+, K0 (1)

(incl. 0) 0,+, + (2)

± (3)

(1) K0 K+, K0 K- by isospin symmetry

(2) Taken from hadron gas fit by

Becattini et al., if not measured.

(3) Empirical factor ( + ) / = 1.6

assumed.

Data: E802, E866, E895, E917, NA49

1.5 (+ + -)

1.5 (+ + -)

Sudden change of strangeness production at sNN = 7-8GeV ?


Particle YieldsLocal Slope of Energy Dep.: s/s-Quarks

Local slope seemsto change quite fastfor strangeness atsNN = 7-8GeV

Smoother dependencefor pions


Particle Yields(Anti-)Strangeness to Pion Ratio

Maximum in strangeness/pion ratio

Same for s and s quarks

Difficult to model in hadronic scenarios Solid line: Statistical hadron gas model with s = 1 K. Redlich, priv. comm.

Predicted as signal for the onset of deconfinementDotted line: M. Gazdzicki and M.I. Gorenstein, Acta Phys. Polon. B30 (1999), 2705


Transverse Mass SpectraEnergy Dependence of mt-m0

Energy dependence of transverse activity seems to change around sNN = 7-8GeV

General feature for pion, kaons and protonsQuite robust observation

negatively charged


Transverse Mass SpectraLocal Slope of Energy Dependence: mt-m0

iNNiNN

itit

NN

t

ss

mm

s

m

1

1Significant change of local slope forpions and kaons around sNN = 7 GeV

Similar for protons


Elliptic FlowEnergy Dependence of v2 for Pions

Initial spatial anisotropy different pressure gradients momentum anisotropy v2

Mid-rapidity data,pt integrated

Energy dependence changes in SPS region


Elliptic FlowModel Comparison of v2 for Pions

H. Petersen, Hot Quarks06

Squeeze-out at lowerenergies not describedw/o nuclear potential

Energy dependence of v2

not described by UrQMD

At higher energies: lack of inital pressure!

Indication for onset ofpartonic flow at SPS?


Elliptic Flowv2 for Protons at 40A GeV

?

NA49PRC 68 (2003) 034903

Disappearance of proton flow?

Evidence for 1st order phase transition H. Stöcker, nucl-th/0406018

Standard method different tocumulant method at mid-rapidity

Larger systematic error

Systematic study with higher precision needed

Challenge for future experiments!


Bose-Einstein CorrelationsEnergy Dependence of Radius Parameters


Bose-Einstein CorrelationsEnergy Dependence of Radius Parameters

kt 0.2GeV/c

No indication for strong energy dependence between AGS and RHIC

Structures?

But: Unresolved discrepanciesbetween SPS experiments!


Bose-Einstein CorrelationsModel Comparison: UrQMD

0

2

4

6

8

10

NA49 data: ; th:

0

2

4

6

8

0

2

4

6

8

0 100 200 300 4000

2

4

6

8

0 100 200 300 400 0 100 200 300 400 500

(20A

GeV

)

kT [MeV/c]

(40A

GeV

)(3

0A G

eV)

(80A

GeV

)

Eb

(160

A G

eV)

Ri [

fm]

O S L

0

2

4

6

8

10

NA49 data20A – 158A GeV

Reasonable description by transport model

(R2out-R2

side)1/2 slightly larger in modelM. Bleicher, GRC06QingFeng Li, Frankfurt


Bose-Einstein CorrelationsModel Comparison: UrQMD

1 10 100 1000 100000

2

4

6

8

0

2

4

6

8

0

2

4

6

8

10

RL (fm

)

Eb (A GeV)

exp (stars):k

T~150: E2,4,6,8,

E20,30,40,80,160 (NA49)k

T~170: s130

kT~200: E10.7,s62.4,s200

E40,80,160 (CERES)

Ro (fm

) R

s (fm

)

Squares: kT=100 MeV/c

Circles: kT=200 MeV/c

No structure in energydependence in data andtransport model

Data

M. Bleicher, GRC06QingFeng Li, Frankfurt


Summary

Evidences for structures in hadronic exciation functionsAround sNN = 7-8GeV

Particle YieldsQualitatively close to to statistical model expectations

Clear deviations seen for kaons and Maxima in X/ ratios as in stat. model ?

Indication for sudden change in strangeness e.-dep.Transverse mass spectra

Sudden change of mtChange of radial flow EOS ?

Elliptic flowNo clear evidence, higher presision data needed

Bose-Einstein correlationsNo evidence for structure

High precision data mandatory!


Thanks!


High pt

Energy Dependence of RCP for Pions and h-

?

RpA

Strongest drop of RCP between s = 17.3GeV and s = 62.4GeV

Any onset at low energies?

SPS


Particle YieldsEnergy Dependence of K+/+

Central Pb+Pb/Au+Au

Mid-rapidity ratios

Same structure as for 4


Particle YieldsEnergy Dependence of 4 Yields

AGS NA49 BRAHMSCentral Au+Au, Pb+Pb

Access to the energy dependence of identified particle yields in the range sNN = 2.5 – 200 GeV


Transverse Mass SpectraInverse Slope Parameters of Kaons

Feature cannot be described by transport models

Y. Hama et al.Braz. J. Phys. 34 (2004), 322, hep-ph/0309192

Hydro calculation withassumption of 1st order phase transition

Change of EOS seen?


Transverse Mass SpectraInverse Slope Parameters of Kaons

Step in energy dependence

p+p compilation from:M. Kliemant, B. Lungwitz, and M. Gazdzicki, PRC 69 (2004) 044903

Seems to be absent in p+p


Transverse Mass Spectra“Hydro” - Model

t

ttt

tt T

pI

T

mKm

dydmm

dN

1

01

tanh

sinhcosh

Basic model: Common freeze-out of all particle types Boost invariant longitudinal expansion Transverse expansion is modelled by a velocity profile “Standard” version:

Schnedermann, Sollfrank, and Heinz,Phys. Rev. C46

Extended version: Resonance contribution included

Baryonic resonances introduce dependence on B

Chemical freeze-out: Tch and B taken from freeze-out curve

Thermal freeze-out: System cools down, therefore assume: Conservation of entropy Conservation of effective particle numbers

U. Wiedemann and U. Heinz, Phys. Rev. C56 (1997) 3265B. Tomasik, nucl-th/0304079


Transverse Mass Spectra“Hydro” – Model Fits

E895: nucl-ex/0306033NA49: Phys. Rev. C66 (2002) 054902, nucl-ex/0403023PHENIX: Phys. Rev. C69 (2004) 024904, nucl-ex/0307022

Convave Resonances

Exponential Shoulder Radial flow

- K- p


Transverse Mass SpectraEnergy Dependence of Fit Parameter

Fit to -, K- and p

Box-shaped source profileand linear velocity profile

Fit range 0.1 < mt-m0 < 0.8 GeV

Energy dependence of Tf seems to change around 30 AGeVThermal and chemical freeze-out different? Single freeze-out model?

Continous increase of T

Tch


Transverse Mass SpectraBlast Wave Fits

Good description of all particle species at SPS energies

Blast wave implementation:F. Retiere andM. Lisa nucl-th/0312024

Fit parameters:

0 oT ,R , , ,


Bose-Einstein CorrelationsBlast Wave Model Fits

Combined fit to HBT radiiand transverse mass spectra

Good fit to the data

slight deviations in Rside at high kt

Blast wave implementationn: M. Lisa, F. Retiere, nucl-th/0312024

2

t2

0

s

(R

u

) 1S(x, K) m cosh( Y) ( , ) exp

2 exp(K / ) 1T

Emission function:

0 oT ,R , , , Fit parameters:


Bose-Einstein CorrelationsThermal Freeze-Out Parameters

Tchem

J. Cleymans, K. Redlich,

Phys. Rev. C60, 054908 (1999)

Slightly increasing temperature with beam energy

Approx. constant transverse geometrical Radii (Rbox 2Rgauss)

Finite emission duration at SPS energies


Bose-Einstein CorrelationsEnergy Dependence of Freeze-Out Volume

D. Adamová et al. (CERES collaboration),Phys. Rev. Lett. 90 (2003) 022301.

Minimum in freeze-outvolume in SPS region

22/32 sidelongf RRV

Possible explanation: Constant mean free path freeze-out condition

Transition baryon meson dominated

N

Vf

ff

1

NNN NN

But: Unresolved inconsistenciesbetween SPS experiments!


Bose-Einstein CorrelationsEnergy Dependence of Freeze-Out Volume

kt 0.15GeV/c


Particle YieldsAntilambda-Antiproton Ratio

Increase above 1 towardslower energies

consistent with recent NA49 data

Models predict ratio < 1Hadron Gas 1: J. Manninen et al.Hadron Gas 2: K. Redlich et al.Hadron Gas 3: J. Rafelski et al.


Particle YieldsAntibaryon-Baryon Ratio

Strong increase of B/B ratioin SPS energy range

Energy dependence weakenswith increasing strangenesscontent

Lines: Statistical hadron gas modelJ. Manninen et al.Fit to 4 data!

NA49 preliminary

No indications for structuresin energy dependence

review of structures in the energy dependence of hadronic observables

Documents

statistical hadron gas

agev snn

hadronic scenarios solid

phase transition

ssquarkslocal slope

systemstatistical model

gev maximum of strangeness

fastfor strangeness