Bulk signatures & properties
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Bulk signatures & properties (soft particle production). Does the thermal model always work ?. Data – Fit ( s ) Ratio. Particle ratios well described by T ch = 160  10 MeV, m B = 24 5 MeV Resonance ratios change from pp to Au+Au  Hadronic Re-scatterings!.

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Bulk signatures & properties (soft particle production)

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Bulk signatures properties soft particle production

Bulk signatures & properties

(soft particle production)


Does the thermal model always work

Does the thermal model always work ?

Data – Fit (s) Ratio

  • Particle ratios well described by Tch = 16010 MeV, mB = 24 5 MeV

  • Resonance ratios change from pp to Au+Au  Hadronic Re-scatterings!


Strange resonances in medium

Strange resonances in medium

Short life time [fm/c]

K* < *< (1520) < 

4 < 6 < 13 < 40

Rescattering vs.

Regeneration ?

Medium effects on resonance and their decay products before (inelastic) and after chemical freeze out (elastic).

Red: before chemical freeze out

Blue: after chemical freeze out


Bulk signatures properties soft particle production

ResonanceProduction in p+p and Au+Au

Life time [fm/c] :

 (1020) = 40

L(1520) = 13

K(892) = 4

++ = 1.7

Thermal model [1]:

T = 177 MeV

mB = 29 MeV

UrQMD [2]

[1] P. Braun-Munzinger et.al., PLB 518(2001) 41

D.Magestro, private communication

[2] Marcus Bleicher and Jörg Aichelin

Phys. Lett. B530 (2002) 81-87.

M. Bleicher, private communication

Rescattering and regeneration is needed !


Resonance yields consistent with a hadronic re scattering stage

Resonance yields consistent with a hadronic re-scattering stage

  • Generation/suppression according to x-sections

p

p

D

p

Preliminary

r/p

p

p

D

L*

D/p

More D

K

Chemical freeze-out

f/K

f Ok

p

p

r

p

p

Less K*

K*/K

p

r

K*

Less L*

L*/L

K

K

f

0.1

0.2

0.3

K


Lifetime and centrality dependence from 1520 and k 892 k

  • Blast wave fit of p,K,p (Tkin +b) + Tchem

  • Dt ~ 6 fm/c

    Based on entropy: Dt ~ (Tch/Tkin – 1) R/bs

  • Dt does not change much with centrality

  • because slight DT reduction is compensated by slower expansion velocity b in peripheral collisions.

preliminary

More resonance measurements are needed

to verify the model and lifetimes

Lifetime and centrality dependence from (1520) / and K(892)/K

G. Torrieri and J. Rafelski, Phys. Lett. B509 (2001) 239

Life time:

K(892) = 4 fm/c

L(1520) = 13 fm/c

  • Model includes:

  • Temperature at chemical freeze-out

  • Lifetime between chemical and thermal freeze-out

  • By comparing two particle ratios (no regeneration)

  • results between :

  • T= 160 MeV =>  > 4 fm/c(lower limit !!!)

  •  = 0 fm/c => T= 110-130 MeV

(1520)/ = 0.034  0.011  0.013

K*/K- = 0.20  0.03 at 0-10% most central Au+Au


Time scales according to star data

hadronic phase

and freeze-out

QGP and

hydrodynamic expansion

initial state

Balance function (require flow)

pre-equilibrium

Resonance survival

hadronization

Rout, Rside

Rlong (and HBT wrt reaction plane)

dN/dt

time

5 fm/c

1 fm/c

10 fm/c

20 fm/c

Chemical freeze out

Kinetic freeze out

Time scales according to STAR data


Identified particle spectra for au au @ 200 gev

BRAHMS: 10% central

PHOBOS: 10%

PHENIX: 5%

STAR: 5%

Identified Particle Spectra for Au-Au @ 200 GeV

  • The spectral shape gives us:

    • Kinetic freeze-out temperatures

    • Transverse flow

  • The stronger the flow the less appropriate are simple exponential fits:

    • Hydrodynamic models (e.g. Heinz et al., Shuryak et al.)

    • Hydro-like parameters (Blastwave)

  • Blastwave parameterization e.g.:

    • Ref. : E.Schnedermann et al, PRC48 (1993) 2462

      Explains: spectra, flow & HBT


Blastwave a hydrodynamic inspired description of spectra

Blastwave: a hydrodynamic inspired description of spectra

Spectrum of longitudinal and transverse boosted thermal source:

bs

R

Ref. : Schnedermann, Sollfrank & Heinz,

PRC48 (1993) 2462

Static Freeze-out picture,

No dynamical evolution to freezeout


Heavy strange particles show deviations in basic thermal parametrizations

STAR preliminary

Heavy (strange ?) particles show deviations in basic thermal parametrizations


Blastwave fits

Blastwave fits

  • Source is assumed to be:

    • In local thermal equilibrium

    • Strongly boosted

  • , K, p: Common thermal freeze-out at T~90 MeV and <>~0.60 c

  • : Shows different thermal freeze-out behavior:

    • Higher temperature

    • Lower transverse flow

  • Probe earlier stage of the collision, one at which transverse flow has already developed

  • If created at an early partonic stage it must show significant elliptic flow (v2)

Au+Au sNN=200 GeV

STAR Preliminary

 68.3% CL

95.5% CL

99.7% CL


Collective radial expansion

Collective Radial Expansion

From fits to p, K, p spectra:

  • <r >

    • increases continuously

  • Tth

    • saturates around AGS energy

  • Strong collective radial expansion at RHIC

  • high pressure

  • high rescattering rate

  • Thermalization likely

Slightly model dependent

here:

Blastwave model


Dynamics indicate common freezeout for most particles

Dynamics indicate common freezeout for most particles

Chemical FO temperature

About 70 MeV difference between Tch and Tth: hadronic phase


Collective anisotropic flow

z

y

x

Collective anisotropic flow


Elliptic flow in the transverse plane for a mid peripheral collision

Elliptic Flow(in the transverse plane)for a mid-peripheral collision

Flow

Y

Out-of-plane

In-plane

Reaction

plane

Flow

X

Dashed lines: hard

sphere radii of nuclei

Re-interactions  FLOW

Re-interactions among what? Hadrons, partons or both?

In other words, what equation of state?


Anisotropic flow

Anisotropic Flow

y

f

x

z

x

Transverse plane

Reaction plane

A.Poskanzer & S.Voloshin (’98)

“Flow” is not a good terminology

especially in high pT regions

due to jet quenching.

0th: azimuthally averaged dist.  radial flow

1st harmonics: directed flow

2nd harmonics: elliptic flow


Hydrodynamics describes the data

Hydrodynamics describes the data

Strong collective flow:

elliptic and radial

expansion with

mass ordering

Hydrodynamics:

strong coupling,

small mean free path,

lots of interactions

NOT plasma-like


V 2 measurements

v2 measurements

Multistrange v2 establishes partonic collectivity ?


Iii the medium consists of constituent quarks

# III: The medium consists of constituent quarks ?

baryons

mesons


Ideal liquid dynamics reached at rhic for the 1 st time

Ideal liquid dynamics –reached at RHIC for the 1st time


A more direct handle

A more direct handle?

  • elliptic flow (v2) and other measurements (not discussed)  evidence towards QGP at RHIC

    • indirect connection to geometry

  • Are there more direct handles on the space-time geometry of collisions?

    • yes ! Even at the 10-15 m / 10-23 s scale !

  • What can they tell us about the QGP and system evolution?


Volumes lifetimes 2 nd law thermodynamics

Volumes & Lifetimes= 2nd Law Thermodynamics

  • Ideal Gas

  • Relativistic Fermi/Bose Gasm=0

  • Pions (3) vs. QGP (37)


Probing source geometry through interferometry hanbury brown twiss hbt photons from stars

The Bottom line…

if a pion is emitted, it is more likely to emit another

pionwith very similar momentumif the source is small

Creation probability r(x,p) = U*U

F.T. of pion source

Measurable!

Probingsource geometry through interferometry(Hanbury-Brown & Twiss (HBT) – photons from stars

p1

r1

x1

p source

r(x)

1 m

x2

r2

p2

experimentally measuring this enhanced probability: quite challenging

5 fm


Bose einstein correlations

Bose-Einstein correlations


Hbt gglp basics

~

P(p1,p2)/P(p1)P(p2) = 1 + | r(p1 - p2) |2

HBT (GGLP) Basics

  • In the simplest approximation, the technique has not changed since before most of you were born

    Goldhaber, Goldhaber, Lee, and Pais, PR 120:300 (1960)

  • For identical bosons/fermions

P(p1,p2;r1,r2) =

Who made first use of this pedagogic picture?

Gaussian source in xi yields Gaussian correlation

in conjugate variable qi=p1i-p2i

But this (plane wave) approximation neglects many effects


Hbt complexities

HBT Complexities

  • We have neglected

    • Final state interactions

      • Coulomb interaction

      • Strong interaction

      • Weak decays

    • Position-momentum correlations

    • Things more subtle, such as special relativity

State of the art analysis incorporates most of these, but not all


Correlation functions for different colliding systems

Au+Au

R ~ 6 fm

p+p

R ~ 1 fm

d+Au

R ~ 2 fm

Correlation functions for different colliding systems

STAR preliminary

C2(Qinv)

Qinv (GeV/c)

Different colliding systems studied at RHIC

Interferometry probes the smallest scales ever measured !


Reminder

Rlong

p1

qside

x1

p2

qout

Rside

qlong

x2

Rout

Rside

Rout

Reminder

  • Two-particle interferometry: p-space separation  space-time separation

source sp(x) = homogeneity region [Sinyukov(95)]

 connections with “whole source” always model-dependent

Pratt-Bertsch (“out-side-long”) decomposition designed to help disentangle space & time


More detailed geometry

p1

Rlong

q

Rside

p2

Rout

beam direction

More detailed geometry

Relative momentum between pions is a vector

 can extract 3D shape information

Rlong – along beam direction

Rout – along “line of sight”

Rside–  “line of sight”


Measured final source shape

central

collisions

mid-central

collisions

peripheral

collisions

Measured finalsource shape

STAR, PRL93 012301 (2004)

Expected evolution:

?


More information

p1

p2

More information

Relative momentum between pions is a vector

 can extract 3D shape information

Rlong – along beam direction

Rout – along “line of sight”

Rside –  “line of sight”

Rout

Rside

study as K grows…


Why do the radii fall with increasing momentum

Why do the radii fallwith increasing momentum ??


Geometric substructure

Geometric substructure?

random (non-)system:

all observers measure the

“whole source”


Why do the radii fall with increasing momentum1

Why do the radii fallwith increasing momentum ??

It’s collective flow !!

Direct geometrical/dynamical evidence

for bulk behaviour!!!


Flow generated substructure

Flow-generated substructure

random (non-)system:

all observers measure the

“whole source”

  • Specific predictions ofbulk global collective flow:

  • space-momentum (x-p) correlations

  • faster (high pT) particles come from

    • smaller source

    • closer to “the edge”


Timescales

Timescales

  • Evolution of source shape

    • suggests system lifetime is shorter than otherwise-successful theory predicts

  • Is there a more direct handle on timescales?


Disintegration timescale

p1

q

p2

Disintegration timescale

Relative momentum between pions is a vector

 can extract 3D shape information

Rlong – along beam direction

Rout – along “line of sight”

 increases with emission timescale

Rside –  “line of sight”

Rout

Rside


Disintegration timescale expectation

Disintegration timescale - expectation

Rischke & Gyulassy, NPA 608, 479 (1996)

3D 1-fluid Hydrodynamics

with

transition

with

transition

“”

“”

  • Long-standing favorite signature of QGP:

  • increase in , ROUT/RSIDE due to deconfinement  confinement transition

  • expected to “turn on” as QGP energy threshold is reached


Disintegration timescale observation

8

8

6

6

RO (fm)

4

4

RS (fm)

1.5

1.25

RO / RS

1.0

increasing collision energy

Disintegration timescale - observation

  • no threshold effect seen

  • RO/RS ~ 1

RHIC


Disintegration timescale observation1

Heinz & Kolb, hep-ph/0204061

An important space-time

“puzzle” at RHIC

- actively under study

Disintegration timescale - observation

  • no threshold effect seen

  • RO/RS ~ 1

  • toy model calculations suggest very short timescales

    • rapid, explosive evolution

    • too explosive for “real” modelswhich explain all other data

N()


Time scales according to star data1

hadronic phase

and freeze-out

QGP and

hydrodynamic expansion

initial state

pre-equilibrium

hadronization

Time scales according to STAR data

Balance function (require flow)

Resonance survival

Rout, Rside

Rlong (and HBT wrt reaction plane)

dN/dt

time

5 fm/c

1 fm/c

10 fm/c

20 fm/c

Chemical freeze out

Kinetic freeze out


Summary global observables

Summary: global observables

  • Initial energy density high enough to produce a QGP

    • e 10 GeV/fm3

      (model dependent)

    • High gluon density

      dN/dy ~ 800-1200

    • Proof for high density matter but not for QGP


Summary of particle identified observables

Summary of particle identified observables

Statistical thermal models appear to work well at SPS and RHIC

  • Chemical freeze-out is close to TC

  • Hadrons appear to be born

    into equilibrium at RHIC (SPS)

  • Shows that what we observe is

    consistent with thermalization

  • Thermal freeze-out is common

    for all particles if radial flow

    is taken into account.

    T and bT are correlated

  • Fact that you derive T,bT is

    no direct proof but it is consistent with thermalization


Conclusion

Conclusion

  • There is no “ “ in bulk matter properties

  • However:

    • So far all pieces point

      indeed to QGP formation

      - collective flow

      & radial

      - thermal behavior

      - high energy density

elliptic


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