helen caines yale university soft physics at the lhc - catania - sept. 2006 questions for the lhc...
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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
Catania – Sept 2006 3
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
Catania – Sept 2006 4
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
Catania – Sept 2006 5
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
Catania – Sept 2006 6
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
Catania – Sept 2006 7
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
Catania – Sept 2006 8
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
Catania – Sept 2006 9
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
Catania – Sept 2006 10
Varying T and R
Calculation for most central Au-Au data
Correlation volume: V0 R0
3
R0 ~ proton radius strong interactions
K. Redlich
Au-Au √sNN = 200 GeV
SPS data indicated
R = 1.1 fm
Can get same E(i) with differing R and T combinations
Helen Caines
Catania – Sept 2006 11
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
Au-Au √sNN = 200 GeV
Helen Caines
Catania – Sept 2006 12
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
Au-Au √sNN = 200 GeV
Helen Caines
Catania – Sept 2006 13
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
Catania – Sept 2006 14
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
Catania – Sept 2006 15
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
Catania – Sept 2006 16
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
Catania – Sept 2006 17
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
Catania – Sept 2006 18
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
Catania – Sept 2006 19
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
Catania – Sept 2006 20
√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
Catania – Sept 2006 21
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
Catania – Sept 2006 22
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
Catania – Sept 2006 23
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
Catania – Sept 2006 24
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
Catania – Sept 2006 25
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
Catania – Sept 2006 26
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
Catania – Sept 2006 27
Fluctuations matter
Important for all Cu-Cu and peripheral Au-Au
PHOBOS QM2005
Helen Caines
Catania – Sept 2006 28
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
Catania – Sept 2006 29
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
Catania – Sept 2006 30
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
Catania – Sept 2006 31
LHC prediction II
Ro = Rs = Rl = 6 fm
Most central events:dNch/d ~1200dNch/d ~10.5
Helen Caines
Catania – Sept 2006 32
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
Catania – Sept 2006 33
62 GeV : Λ , Ξ central Backup Ideal Hydrodynamics
Helen Caines
Catania – Sept 2006 34
Λ , Ξ centrality dependence Backup Ideal Hydrodynamics
NNAu+Au, s = 62.4 GeV NNAu+Au, s = 62.4 GeV
Helen Caines
Catania – Sept 2006 35
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
Catania – Sept 2006 36
Helen Caines
Catania – Sept 2006 37
Helen Caines
Catania – Sept 2006 38
Helen Caines
Catania – Sept 2006 39
Chemistry in forwards direction
BRAHMS PRELIMINARY
b drives the production ratios – Where does LHC sit?
Differences appearing in p-p production
Helen Caines
Catania – Sept 2006 40
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
Catania – Sept 2006 41
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