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The freeze-out source shape: recent results from the STAR energy scan. Mike Lisa (Ohio State University) for the STAR Collaboration. Outline. general motivation RHIC BES program asHBT a growing database of asHBT systematics (another) anomalous behaviour at SPS? new STAR data

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the freeze out source shape recent results from the star energy scan

The freeze-out source shape:recent results from the STAR energy scan

Mike Lisa (Ohio State University)

for the STAR Collaboration

outline
Outline
  • general motivation
    • RHIC BES program
    • asHBT
  • a growing database of asHBT systematics
    • (another) anomalous behaviour at SPS?
    • new STAR data
    • reconciling RHIC, SPS results?
      • centrality cuts
      • RP resolution correction schemes
      • rapidity(underway)
  • conclusion

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

rhic energy scan s 7 40 gev 2010 2012
RHIC energy scan: √s=7-40 GeV(2010~2012 (?))
  • Probe QCD phase diagram via
  • statistics/fluctuations
  • dynamic system response
    • transport models (phase structure in EoS)
    • bulk collectivity (low-pT measurements)

Kolb&Heinz 2000

Brachmann et al,PRC 2000

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

slide4

Central Au+Au @ 7.7 GeV event in STAR TPC

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

slide5

http://drupal.star.bnl.gov/STAR/starnotes/public/sn0493

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

slide6

Status as of Oct 5 2011

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

phi the sexy direction
phi- the sexy direction
  • evolution from initial “known” shape depends on
  • pressure anisotropy (“stiffness”)
  • lifetime
  • Both are interesting!
  • We will measure a convolution over freezeout
    • model needed

0 fm/c

2 fm/c

4 fm/c

6 fm/c

8 fm/c

P. Kolb, PhD 2002

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

phi the sexy direction1
phi- the sexy direction

0 fm/c

2 fm/c

4 fm/c

6 fm/c

8 fm/c

O’Hara et al, Science 2002

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

slide9

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3 into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

slide10

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3 into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

  • energy quickly deposited
  • transition to deconfined (plasma) phase
  • hydrodynamic expansion
  • cool back to confined (atomic) phase

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

slide11

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3 into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

  • energy quickly deposited
  • transition to deconfined (plasma) phase
  • hydrodynamic expansion
  • cool back to confined (atomic) phase

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

slide12

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3 into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

  • energy quickly deposited
  • transition to deconfined (plasma) phase
  • hydrodynamic expansion
  • cool back to confined (atomic) phase
  • probe EoSunder extreme conditions (√s dep.)

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

slide13

Microexplosion

Femtoexplosion

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

Extremely high pressures (∼10  TPa) and temperatures (5×105  K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014   W/cm2 converting material within the absorbing volume of ∼0.2  μm3 into plasma in a few fs. A pressure of ∼10  TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018  K/s can, thus, be studied in a well-controlled laboratory environment.

measure momentum

infer geometry

measure geometry

infer momentum

  • energy quickly deposited
  • transition to deconfined (plasma) phase
  • hydrodynamic expansion
  • cool back to confined (atomic) phase
  • probe EoSunder extreme conditions (√s dep.)
  • examine final shape/size of system

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

measuring lengths

C(Qout)

typical “Gaussian” fitting function

C(Qside)

C(Qlong)

big RS

measuring lengths

1/RSIDE

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

measuring shape

small RS

C(Qout)

C(Qside)

C(Qlong)

big RS

measuring shape

1/RSIDE

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

measuring shape1
measuring shape

side

out

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

measuring shape2
measuring shape

side

more info. six “HBT radii”

out

R2out-side < 0

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

azimuthal dependence of hbt radii at rhic
Azimuthal dependence of HBT radii at RHIC

STAR, PRL93 012301 (2004)

Retiere&MAL PRC70 (2004) 044907

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

azimuthal dependence of hbt radii at rhic1
Azimuthal dependence of HBT radii at RHIC

STAR, PRL93 012301 (2004)

“No-flow formula” estimated good within ~ 30% (low pT)

Retiere&MAL PRC70 (2004) 044907

Mount et al, PRC84:014908,2011

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

welcome to the machine
Welcome to the machine

It’s a bit more complicated than using a microscope like the femtosecond laser guys do...

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

welcome to the machine1
Welcome to the machine

4 (8) 3D corr. functions

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

welcome to the machine2
Welcome to the machine

4 (8) 3D corr. functions

4 (8) RP-corrected CFs

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

welcome to the machine3
Welcome to the machine

4 (8) sets of 4 (6) radii

4 (8) 3D corr. functions

4 (8) RP-corrected CFs

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

welcome to the machine4
Welcome to the machine

4 (8) sets of 4 (6) radii

4 (8) 3D corr. functions

4 (8) RP-corrected CFs

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

7 (9) Fourier Coefficients

welcome to the machine5
Welcome to the machine

4 (8) sets of 4 (6) radii

4 (8) 3D corr. functions

4 (8) RP-corrected CFs

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

7 (9) Fourier Coefficients

1 eccentricity estimate

welcome to the machine6
Welcome to the machine

4 (8) sets of 4 (6) radii

4 (8) 3D corr. functions

4 (8) RP-corrected CFs

~30%

see, e.g. E. Mount et al PRC84:014908,2011

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

7 (9) Fourier Coefficients

1 eccentricity estimate

generic expectation
Generic expectation

0 fm/c

lifetime, “push”

2 fm/c

4 fm/c

6 fm/c

8 fm/c

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

an excitation function begging for more
An excitation function begging for more

0 fm/c

2 fm/c

4 fm/c

RHIC scan

6 fm/c

  • non-monotonic excitation function of bulk observable?
    • interesting in proposed scan region
    • but: tilt issue – need 1st-order plane in scan!!

8 fm/c

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

a pleasant daydream
A pleasant daydream

Focus on effect of EoS. Keep εinit and effective lifetime fixed

sound speed

early “stiffness”

εinit

ε

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

a pleasant daydream1
A pleasant daydream

Focus on effect of EoS. Keep εinit and effective lifetime fixed

sound speed

early “stiffness”

εinit

ε

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

an excitation function begging for more1
An excitation function begging for more

0 fm/c

2 fm/c

4 fm/c

RHIC scan

6 fm/c

  • non-monotonic excitation function of bulk observable?
    • interesting in proposed scan region
    • but: tilt issue – need 1st-order plane in scan!!
  • reminiscent of (unobserved) non-monotonic v2(root(s))

8 fm/c

Sollfrank, Kolb, Heinz, nucl-th/0061292

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

transport predictions or untuned postdictions
transport predictions (or “untunedpostdictions”)

Lisa et al, New J. Phys 2011

  • naive expectation: absent something special, monotonic decrease
  • higher energy  more pressure  evolve to smaller εF
  • higher energy  longer lifetime  evolve to smaller εF
  • (hybrid models – special case)
  • certainly no minimum

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

10 years of ashbt systematics

2000 : E895/AGS

PLB496 1 (2000)

10+ years of asHBT systematics

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

10 years of ashbt systematics1

2000 : E895/AGS

  • PLB496 1 (2000)
  • 2004: STAR/RHIC
  • 200 GeV
  • PRL93 012301 (2004)
10+ years of asHBT systematics

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

10 years of ashbt systematics2

2000 : E895/AGS

  • PLB496 1 (2000)
  • 2004: STAR/RHIC
  • 200 GeV
  • PRL93 012301 (2004)
  • 2008: CERES/SPS
  • PRC78 064901 (2008)
10+ years of asHBT systematics

!? Something special?

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

10 years of ashbt systematics3

2000 : E895/AGS

  • PLB496 1 (2000)
  • 2004: STAR/RHIC
  • 200 GeV
  • PRL93 012301 (2004)
  • 2008: CERES/SPS
  • PRC78 064901 (2008)
  • 2010 (WPCF Kiev):
  • STAR/RHIC 62.4 GeV
10+ years of asHBT systematics

!? Something special?

!? A real minimum? – speculation of P.T. (Lisa et al, New J. Phys 2011)

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

10 years of ashbt systematics4

2000 : E895/AGS

  • PLB496 1 (2000)
  • 2004: STAR/RHIC
  • 200 GeV
  • PRL93 012301 (2004)
  • 2008: CERES/SPS
  • PRC78 064901 (2008)
  • 2010 (WPCF Kiev):
  • STAR/RHIC 62.4 GeV
  • 2011 (QM Annecy):
  • STAR/RHIC
  • 7.7, 11.5, 39 GeV
  • arXiv:1107.1527
10+ years of asHBT systematics

!? Something special?

!? A real minimum? – speculation of P.T. (Lisa et al, New J. Phys 2011)

!!!? A real sharp minimumat the “special” kink/horn/step energy?

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

10 years of ashbt systematics5

2000 : E895/AGS

  • PLB496 1 (2000)
  • 2004: STAR/RHIC
  • 200 GeV
  • PRL93 012301 (2004)
  • 2008: CERES/SPS
  • PRC78 064901 (2008)
  • 2010 (WPCF Kiev):
  • STAR/RHIC 62.4 GeV
  • 2011 (QM Annecy):
  • STAR/RHIC
  • 7.7, 11.5, 39 GeV
  • arXiv:1107.1527
  • 2011 (WPCF Tokyo)
  • STAR/RHIC
  • 19.6 GeV
  • 2011 (WPCF Tokyo)
  • PHENIX/RHIC
  • 200 GeV
  • Soon: ALICE/LHC
10+ years of asHBT systematics

PHENIX – WPCF 2011 (10-30%)

!? Something special?

!? A real minimum? – speculation of P.T. (Lisa et al, New J. Phys 2011)

!!!? A real sharp minimumat the “special” kink/horn/step energy?

Uh-oh

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

the beauty of a single collider detector
the beauty of a single, collider detector

Au+Au 7.7 GeV

Au+Au 39 GeV

Au+Au 200 GeV

Identical techniques, systematics,

acceptance...

BUT: cannot get complacent

Important measurement, and cross-checks are important, if we take data at all seriously.

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

can ceres and star be reconciled
can CERES and STAR be reconciled?
  • at this point, the energies measured are too close to reasonably expect such a difference.
  • What else could it be?
  • different reaction-plane resolution correction technique?
  • different centrality?
  • different fitting parameters?
  • different rapidity range?

New J. Phys. 13065006 (2011)

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

welcome to the machine7
Welcome to the machine

4 (8) sets of 4 (6) radii

4 (8) 3D corr. functions

4 (8) RP-corrected CFs

Reaction-plane resolution correction:

STAR: RP resolution correction done bin-by-bin to correlation functions

CERES: correction done to HBT radius parameters (similar to v2)

(question to CERES: was finite bin-width also accounted for? (Δ/2)/sin(Δ/2)) ~5% effect)

R. Wells PhD thesis (2002): methods yielded similar results in that case

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

7 (9) Fourier Coefficients

1 eccentricity estimate

rp resolution correction
RP resolution correction

very small effect in STAR analysis

Similar at other energies

No guarantee this will be true for any other experiment, but probably not the issue

correcting CFs

correcting radii

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

centrality
Centrality

0%

20%

30%

40%

50%

10%

E895

CERES

STAR

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

centrality1
Centrality

0%

20%

30%

40%

50%

10%

E895

CERES

STAR

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

centrality2
Centrality

0%

20%

30%

40%

50%

10%

E895

CERES

STAR

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

centrality3
Centrality

0%

20%

30%

40%

50%

10%

E895

CERES

STAR

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

centrality4
Centrality

0%

20%

30%

40%

50%

10%

E895

CERES

STAR

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

fitting techniques
Fitting techniques

symmetry [Phys. Rev. C66, 044903 (2002)]: vanish at y=0

no 1st-order oscillations at any y, using 2nd-order RP

6 radii:

no symmetry rule against λ, oscillation, but keeping it fixed reduces #parameters

small effect

(maybe more than gut intuition?)

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

can ceres and star be reconciled1
can CERES and STAR be reconciled?
  • at this point, the energies measured are too close to reasonably expect such a difference.
  • What else could it be?
  • different reaction-plane resolution correction technique?
  • different centrality?
  • different fitting parameters?
  • different rapidity range?  presently under investigation in data (models may help, too)

New J. Phys. 13065006 (2011)

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011

summary outlook
summary & outlook
  • asHBT in HIC: probe for non-trivial structure on the QCD phase diagram
    • unique, valuable information, but nontrivial analysis...
    • models show significant sensitivity to important physics
  • growing systematics of asHBT over the past decade
    • intriguing possible minimum in ε(√s) not supported by preliminary STAR BES
    • other than CERES point, slow gradual decrease of eccentricity with √s
    • any possible structure would be remarkably narrow
    • remarkable agreement with prediction of UrQMD
    • PHENIX pions at 200 GeV agree with STAR
      • PHENIX also reports kaons!
  • outlook
    • rapidity study in STAR in continuing attempt to understand CERES and develop systematic errors
    • 1st-order, 3rd-order studies in STAR & PHENIX
    • ongoing asHBT studies in ALICE

ma lisa - Workshop On Fluctuations, Correlations and RHIC Low Energy Runs - Brookhaven National Lab - Oct 2011