Helen Caines Yale University Soft Physics at the LHC - Catania - Sept. 2006 Questions for the LHC...

Helen CainesYale University

Soft Physics at the LHC - Catania - Sept. 2006

Questions for the LHC resulting from RHIC Strangeness

Outline

• Chemistry• Yields - Centrality dependence• Flow (radial and v2)• Intermediate pT

Helen Caines

Catania – Sept 2006 2

p-p data

•Not just a base line!

•Interesting results in their own right.

•Need to push for p-p at the same energy.

•mT scaling - not absolute

Separate shape for baryons and mesons

Not really going to discuss – see Rene’s talk

STAR Preliminary p-p 200 GeV

Helen Caines


mT scaling and jetsUsing PYTHIA split events into gluon and quark jet

Quark jet events show mass dependence

Gluon jet events show baryon/meson splitting

Gluon jet domination at RHIC? What happens at the LHC?

Helen Caines


Statistical model results

●, K,p●, K,p, ,

TTLQCDLQCD~160-170MeV~160-170MeVTTLQCDLQCD~160-170MeV~160-170MeV

●, K,p●, K,p, ,

Including is important for s

Close to chem. equilibrium !

Close to net-baryon free

Tch flat with centrality

How fast does LHC reach s =1?

STAR preliminary Au+Au at √sNN=200GeV and 62 GeV

Using Kaneta model

Helen Caines


Expectations at the LHC energies Tch 125 - 170 MeV

Calculations fromKraus et al., (Eq.)Rafelski et al., (Non Eq.)

Statistical model predictions for LHC

Measurable differences in

predictions from the models

s 1-5

Helen Caines


Strangeness meets heavy flavour

STAR Preliminary

d-Au √s=200 GeV

3.00

D

D

2.00

D

Ds

1.1

s

s

D

D

16.00

Dc

PYTHIA tells us:

4.00

D

D

4.00

D

Ds

.1

s

s

D

D

16.00

Dc

Statistical recombination tells us:

A. Andronic et al. PLB 571 (2003)

Ds (BR 3.6%)+

Use a “resonance” analysis technique K+K-

Our total charm cross-section calc. could be affected

After background subtraction

Should be feasible at LHC – more charm

Helen Caines


Excitation function of central mid-rapidity yields

Baryon yields ~flatAnti-baryon rise sharply

dN/dy extrapolations at the LHC : 10~30 : 3~6 : 0.4~0.7

Helen Caines


Centrality dependence

We can describe p-p and central Au-Au

Can we understand 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

Even without p-p LHC can determine centrality dependence

Helen Caines


The canonical to grand canonical transition

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


Varying T and R

Calculation for most central Au-Au data

Correlation volume: V0 R0

3

R0 ~ proton radius strong interactions

K. Redlich


SPS data indicated

R = 1.1 fm

Can get same E(i) with differing R and T combinations

Helen Caines


Npart dependence

STAR Preliminary

K. Redlich

Correlation volume:

V= (ANN) ·V0

ANN = Npart/2 V0 = 4/3 ·R0

3

R0 = 1.2 fm proton radius/strong interactions

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

Shape described if production volume not prop. Npart


Helen Caines


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

Similar enhancementfor one s hadrons


Helen Caines


Soft physics scalings with entropy (Nch)

PHOBOS White Paper: Nucl. Phys. A 757, 28

nucl-ex/0505014 Lisa et al.

<kT>≈ 400 MeV (RHIC) <kT>≈ 390 MeV (SPS)

HBT radii from different systems and different energies scale with (dNch/dη)1/3

v2 scaling within “low density limit” scalingwhen use part

These are all scalings over several orders of magnitude of √s

Most central LHC:dNch/d ~1200

Helen Caines


Strangeness vs entropy

No scaling between energies

But does become ~linear at higher dNch/d

Solid – STAR Au-Au √sNN = 200 GeV

Hollow - NA57 Pb-Pb √sNN = 17.3 GeV

Most central LHC:dNch/d ~1200

dN/dy = dN/dy ~20-30

dN/dy = dN/dy ~4-6

dN/dy = dN/dy ~0.5-1

Helen Caines


Blast-wave

• Blast-Wave: hydro inspired parameterization:– Parameter Tkin

– Parameter <βT>– Direct fit (2) on the

data

• Blast-Wave gives slightly different results for multi-strange

• At 62 GeV <βT> lower

~ 90 MeV

~ 160 MeV

~ 125 MeV

NA57 : C. Alt et al. Phys. Rev. Lett 94 (2005) 192301

E. Schnedermann et al., Phys. Rev. C 48 (1993) 2462F. Retière and M. Lisa, Phys. Rev. C 70 (2004) 044907

Blast-Wave :

Helen Caines


Ideal hydrodynamics -, K-, p

• Best agreement for :

Tdec= 100 MeV α = 0.02 fm-1

α ≠ 0 : importance of initial conditions

0 = 0.6 fm/c

Tdec = 165 MeVTdec = 100 MeV α : initial (at τ0) transverse

velocity : vT(r)=tanh(αr)

Central Data

P.F. Kolb, J. Sollfrank and U.Heinz, Phys. Rev. C 62 (2000) 054909P.F. Kolb and R. Rapp, Phys. Rev. C 67 (2003) 044903P.F. Kolb and U.Heinz, nucl-th/0305084

Starts to fail earlier (lower pT)less re-scattering?

Helen Caines


Tdec = 164 MeVTdec = 100 MeV

Ω- spectra, central

Ideal hydro and the

• Both energies best reproduced with Tdec≈100 MeV (as -, K-, p)

• Tdec ≈ 164 MeV (Tch) :Not enough flow

P.F. Kolb and U. Heinz, nucl-th/0305084

If not same physical quantity stick to hydro.

Need better models (hydro+hadronic phase)

• B-W fit on hydro : Tkin ≠ Tdec (up to 30 MeV difference)

Au-Au 200 GeV

Helen Caines


v2 of strange hadrons

All strange particles flow - s quark flow same as light quarkIndication for collective flow in partonic phase (small hadronic x-section for Ω, φ)

Baryon “remembers” it was incoming

STAR Preliminary

Helen Caines


Constituent quark scaling of v2

STAR Preliminary

Au-Au 62 GeV

High statistics data show idealized scaling fails at 200 GeVSee scaling at 62 GeV

Where at LHC (if at all) will hydro/reco switch occur?

PHENIX (open symbols) PRL 91 182301 (2003)

v2 saturates for pT > 3 GeV/c

Clear baryon/meson difference at intermediate to high pT

Helen Caines


√sNN=62 GeV 0-5%

40-60%

Nuclear modification factors - RCP

√sNN=200 GeV 0-5%

40-60%

NA57 nucl-ex/0507012

√sNN=17.3 GeV

0-5/40-55%

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

Differences between and

B absorption?

Helen Caines


Rcp vs Energy

STAR Preliminary

NA57: G. Bruno, A. Dainese: nucl-ex/0511020

The top SPS and top RHIC energy

data are consistent

62 GeV Au+Au data also follows the same trend

Is coalescence present in all

systems?

Does same pattern exist at LHC and out to higher pT?

Helen Caines


Summary• Stat. models predict little change in strangeness at LHC unless over-saturation occurs

• What about charm?• Transition of strangeness from p-p to A-A not well understood

• No Npart scaling• Several soft sector variables scale with dNch/d(i.e. entropy)

• HBT, v2 at low densities, strangeness centrality dependence

• Hydro does not need early multi-strange freeze-out• Need more complex models

• v2 of s quarks same as for light quarks• Baryons retain “memory” of beam?

•Reco. traits observed at all energies – v2 , RcpNew & detailed results from RHIC but as many new soft

physics questions remain for LHC as have been answered

Helen Caines


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

Helen Caines


Recent ReCo Model PredictionsPremise:

Observable:

STAR Preliminary

The production of Φ and Ω particles is almost exclusively

from thermal s quarks even out to 8 GeV/c

The ratio of Ω/ yields should rise linearly with pT

Helen Caines


HBT radii

Entropy determines radii

No obvious trends as fn of √s

HBT radii from different systems and at different energies scale with (dNch/dη)1/3

power 1/3 gives approx. linear scale

nucl-ex/0505014 Lisa et al.

<kT>≈ 400 MeV (RHIC) <kT>≈ 390 MeV (SPS)

Works for different mT ranges

Helen Caines


Eccentricity and low density limit

At hydro. limit v2 saturates

At low density limit

Apparent complete failure.Especially at low density!

Voloshin, Poskanzer PLB 474 (2000) 27

v2 different as fn Npart and energy

eccentdy

dN

Area

1v2

2y

2x

2y

2x

RR

RR eccent

PHENIX preliminary

Helen Caines


Fluctuations matter

Important for all Cu-Cu and peripheral Au-Au

PHOBOS QM2005

Helen Caines


PHOBOS preliminary h±

0-50% centrality

v 2

Elliptic flow

PHENIX preliminary

v2 decreases by ~ 50% from RHIC to SPS

PHENIX preliminary

v2 same for 200 – 62 GeV Au-Au at fixed pT

v2 same in Au-Au and Cu-Cu for same centrality

No perfect scaling but hints

Helen Caines


Nch as measure of entropy

Entropy in Heavy Ion

> Entropy in p-p?

J.Klay Thesis 2001

F~N

π~

V

S

p

Different EOS? QGP?

1/4

NN

3/4NNN

3/4

s

)2ms(F

ε~V

S

Helen Caines


PHOBOS White Paper: Nucl. Phys. A 757, 28

1000 5.5 TeV

5

6

6.4 = RHICx1.6

Most central events:

dNch/d ~1200

LHC prediction I

Helen Caines


LHC prediction II

Ro = Rs = Rl = 6 fm

Most central events:dNch/d ~1200dNch/d ~10.5

Helen Caines


LHC prediction III

Most central events:dNch/d ~1200S ~ 20

But I suspect I’m not in the low density limit any more so

v2/ ~ 0.2

Helen Caines


62 GeV : Λ , Ξ central Backup Ideal Hydrodynamics

Helen Caines


Λ , Ξ centrality dependence Backup Ideal Hydrodynamics

NNAu+Au, s = 62.4 GeV NNAu+Au, s = 62.4 GeV

Helen Caines


Compilation of comparisons

• Use π, K, p B-W parameters on multi-strange baryons– Tkin = 90 - 100 MeV

– <βT> = 0.57 c

• Ξ- and Ω- spectra not reproduced

J. Speltz (for the STAR Collaboration), nucl-ex/0512037

NNAu+Au, s = 62.4 GeV

• Differences between Ξ-, Ω-

and π, K, p mainly due to <βT> (best constrained)

Backup

Helen Caines


Helen Caines


Chemistry in forwards direction

BRAHMS PRELIMINARY

b drives the production ratios – Where does LHC sit?

Differences appearing in p-p production

Helen Caines


Mid-rapidity net-proton yield

62.4 GeV: PHOBOS Preliminary200 GeV: PHENIX PRC 69, 024904 (2004) (correlated errors assumed: underestimated errors)

• Net protons (p–p) yield proportional to Npart (within errors!)

Really “strange” result:

• Number of protons‘transported’ to midrapidityper participant pair isindependent of numberof collisions per participant!

PHOBOS

Preliminary

If net baryons remain at LHC need better description of how transport occurs

Helen Caines


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

0-5% Au-Au √sNN = 200 GeV

All models not the same

Statistical model calculations

STAR Preliminary

Helen Caines Yale University Soft Physics at the LHC - Catania - Sept. 2006 Questions for the LHC...

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