Helen CainesYale University

SQM – L.A.– March 2006

Using strange hadron yields as probes of dense matter.

Outline

• Can we use thermal models to describe the data?• Can we describe the multiplicity trends?• How do the bulk effects extend into the high pT regime?

Helen Caines

SQM – L.A. - March 2006 2

Models readily available to experimentalists

Models 4 parameter Fit

SHARE V1.2 THERMUS V2

Authors M. Kaneta et al.

G. Torrieri, J. Rafelski et al.

S. Wheaton and J. Cleymans

Ensemble Grand Canonical

Grand Canonical

Canonical and Grand Canonical

Parameters T, q, s , s T, q , s , s, q , I3, N, C , C

T, B, S, Q, s, R

T, B, S , q, C, s

, C , R

Feed Down possible default is with % feed-down

default is no feed- down (harder to manipulate)

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SQM – L.A. - March 2006 3

First make a consistency check

Require the models to, in principle, be the same.

• Only allow the least common multiple of

parameters: T, q, s, s

• Use Grand Canonical Ensemble.

• Fix weak feed-down estimates to be the same (i.e. at 100% or 0%).

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The results

Ratio STAR Preliminary

p/p

p

1.01±0.02

0.96±0.03

0.77±0.04

0.15±0.02

0.082±0.009

0.054±0.006

0.041±0.005

(7.8±1) 10-3

(6.3±0.8) 10-3

(9.5±1) 10-4

1.01±0.08

after feed-down

increase s

decrease T

1 error

Not identical and feed-down really matters

Similar T and s

Significantly different errors.

Au-Au √sNN = 200 GeV

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SQM – L.A. - March 2006 5

“Best” predictions (with feed-down) 0-5%THERMUS

B 45 ± 10 MeV

S 22 ± 7 MeV

Q -21 ± 8 MeV

T 168 ± 6 MeV

s 0.92 ± 0.06

SHARE

q 1.05 ± 0.05 (23 MeV)

s 1.02 ± 0.08 (5 MeV)

T 133 ± 10 MeV

s 2.03 ± 0.6

q 1.65 ± 0.5

s 1.07 ± 0.2

Kaneta

B 8.0 ± 2.2 MeV

S -10.3 ± 4.5 MeV

T 154 ± 4 MeV

s 1.05 ± 7

Au-Au √sNN = 200 GeVSTAR Preliminary

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SQM – L.A. - March 2006 6

Comparison between p-p and Au-Au

T 171 ± 9 MeV

s 0.53 ± 0.04

r 3.49 ± 0.97 fm

Canonical ensemble

T 168 ± 6 MeV

s

0.92 ± 0.06

r 15 ± 10 fm

Au-Au √sNN = 200 GeVSTAR Preliminary

p-p √s = 200 GeVSTAR Preliminary

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SQM – L.A. - March 2006 7

Centrality dependence

We can describe p-p and central Au-Au average ratios.

Can we detail the centrality evolution?

Look at the particle enhancements.

E(i) = YieldAA/Npart Yieldpp /2

STAR Preliminary

Solid – STAR Au-Au √sNN = 200 GeV

Hollow - NA57 Pb-Pb √sNN = 17.3 GeV

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SQM – L.A. - March 2006 8

Centrality dependence

STAR Preliminary• Use stat. model info:

C – p-p Strangeness suppressed

GC – central A-A Strangeness saturated

• Transition describes E(i) behaviour

• T =170-165 MeVassume same T for p-p and Au-Au

K. Redlich

Au-Au √sNN = 200 GeV

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SQM – L.A. - March 2006 9

Varying T and R

Calculation for most central Au-Au data

Correlation volume: V0 R0

3

R0 ~ proton radius strong interactions

Rapid increase in E(i) as T decreases

SPS data indicated R = 1.1 fm K. Redlich

Au-Au √sNN = 200 GeV

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SQM – L.A. - March 2006 10

Centrality dependence

STAR Preliminary

K. Redlich

Correlation volume:

V= (ANN) ·V0

ANN = Npart/2 V0 = 4/3 ·R0

3

R0 = 1.1 fm proton radius/strong interactions

T = 170 MeVT = 165 MeV

Seems that T=170 MeV fits data best – but shape not correct

Au-Au √sNN = 200 GeV

Helen Caines

SQM – L.A. - March 2006 11

Npart dependence

STAR Preliminary

K. Redlich

Correlation volume:

V= (ANN) ·V0

ANN = Npart/2 V0 = 4/3 ·R0

3

R0 = 1.1 fm proton radius/strong interactions

T = 165 MeV = 1T = 165 MeV = 2/3T = 165 MeV = 1/3

Seems to be a “linear” dependence on collision geometry

Au-Au √sNN = 200 GeV

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PHOBOS: Phys. Rev. C70, 021902(R) (2004)

More on flavour dependence of E(i)

STAR Preliminary

PHOBOS:

measured E(ch)for 200 and 19.6 GeV

Enhancement for all particles?

Yes – not predicted by model

STAR Preliminary

Similar enhancementfor one s hadrons

Au-Au √sNN = 200 GeV

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SQM – L.A. - March 2006 13

Can we describe √s dependence?

N.B.: SPS energy only 17 GeV

There’s a correlation between dNch/d and Npart/2

If know npp can predict yield at any Npart

small dotted lines are:

dNch/dnpp(1-x)Npart/2 + xNbin

npp= Yield in pp

= 2.29 ( 1.27)

x = 0.13

PHOBOS: Phys. Rev. C70,

021902(R) (2004)

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Strangeness and dNch/d

SPS and RHIC data follows similar curves as a func. of dNch/dη at mid-rapidity

NA57 dNch/dη (pBe) =1.64

STAR dNch/dη (pp) =2.12

Look at yields relative to pp

STAR PreliminarySolid – STARHollow – NA57

Entropy alone seems to drive much of the soft physics

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SQM – L.A. - March 2006 15

RAA – Beyond the bulk

Effect increases as strange

content of baryon increases.

Canonical suppression in p+p?

Rcp Raa

√sNN = 200 GeVSTAR Preliminary

√sNN = 200 GeV

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SQM – L.A. - March 2006 16

RAA for central and peripheral data

Peripheral and central data both show an enhancement

Peripheral data is more enhanced – Cronin effect?

Au-Au √sNN = 200 GeVSTAR Preliminary

Au-Au √sNN = 200 GeVSTAR Preliminary

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SQM – L.A. - March 2006 17

RAA - A mocked upstring picture does well

Topor Pop et al. hep-ph/0505210

HIJING/BBar + KT ~ 1 GeVStrong Color Field (SCF) qualitatively describes RAA.

SCF - long range coherent fields

SCF behavior mimicked by doubling the effective string tension

SCF only produced in nucleus-nucleus collisions RAA≠ RCP

Are strong color fields the answer?

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SQM – L.A. - March 2006 18

Nuclear modification factors - RCP

√sNN=200 GeV

√sNN=62 GeV 0-5%

40-60%

0-5%

40-60%

NA57, PLB in print, nucl-ex/0507012

√sNN=17.3 GeV

First time differences between and

B absorption?

Recombination or different “Cronin” for and K at SPS?

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STAR Preliminary

NA57: G. Bruno, A. Dainese: nucl-ex/0511020Baryon/meson splitting at SPS and RHIC is the

same

62 GeV Au+Au data also

follows the same trend

Recombinationpresent in all

systems?

The Rcp double ratio

What about other centralities?

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SQM – L.A. - March 2006 20

Conclusions• Not all thermal models are the same – even when you try and

make them so.

• The enhancement of strangeness as a function of centrality CAN be described– scales with Npart

1/3 NOT Npart

• Non-strange particles are enhanced – NOT predicted by phase space models.

• Using dNch/dη better than Npart. This is a physical observable unlike Npart.

• The phase space effects of p-p extend into high pT regime.

• Baryon/meson splitting energy independent.

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SQM – L.A. - March 2006 21

Multiplicity scaling with log(√s)

PHOBOS White Paper: Nucl. Phys. A 757, 28, nucl-ex/0410022

If I can describe dNch/das function of√s

Can we describe other observables in terms of dNch/dη ?

dNch/dη - strongly correlated to the entropy of the system!

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SQM – L.A. - March 2006 22

HBT and dNch/d

HBT radii ~linear as a function

Npart1/3

Even better in (dNch/d)1/3

power 1/3 gives approx. linear scale

nucl-ex/0505014 M.Lisa et al.

Scaling works across a large energy range