Does Hadronization happen via Cluster formation?
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Transcript of Does Hadronization happen via Cluster formation?
Does Hadronization happen via Cluster formation?
J. Cleymans I. KrausH. Oeschler K. Redlich
SQM2008, Beijing, Oct.7th, 2008
Chemical Freeze Out
J. Cleymans and K. Redlich, PRL 81 (1998) 5284
NA49 Data - 158 AGeV
Ingrid Kraus et al.,
Phys. Rev. C76 (2007) 064903Corr. vol. NOT prop to Apart
Canonical Suppression (SHM)
Pion density
n(π) = exp(-Eπ/T)
Strangeness is conserved!
Kaon density
NN N Λ K+
n(K) = exp(-EK/T)
[g V ∫ … exp[-(EΛ-µB)/T]
J. Cleymans, HO, K. Redlich,
PRC 60 (1999)
Canonical Suppression
can./grand can.
Example:
T = 170 MeV
μB = 1 MeV
Values for LHC
ΔS=1ΔS=3
Three options for SHM calculations:
a) Canonical with R given by system size
b) Additionally strangeness suppression via γs
c) Canonical suppression is controlled by RC which can differ from the system size R (cluster!)
I. Kraus, J. Cleymans, H. O., K. Redlich,
System size: Phys. Rev. C76 (2007) 064903
R
RC
Phys. Rev. C76 (2007) 064903
System size (and energy dep.) of cluster size
• A+A: clusters smaller than fireball
• RC not well defined for RC ≥ 2 fm because suppression vanishes
RC
= R
Pb+PbAu+Au
For heavy systems possibly the correlation volume extends over about 2-3 fm.
Then no canonical suppression can be observed in the particle ratios!
Same three options for pp collisions:
a) Canonical with R given by system size
b) Additionally strangeness suppression via γs
c) Canonical suppression is controlled by RC which can differ from the system size R (cluster!)
I. Kraus, J. Cleymans, H. O., K. Redlich,
pp: arXiv:0808:0611
R
RC
T = 165 MeV, μB = 220 MeV
b) γS = 0.7
c) RC = 1.0 ± .3 fm, R = 1.4 fm
T = 165 MeV, μB = 14 MeV
b) γS ~ 1
c) RC ~ R = 1.3 fm
p+p
I. Kraus et al., arXiv:0808.0611
Extrapolation to LHC for pp
?
Predictions for pp at LHCPrediction for
heavy ions:
Grand can.
I. Kraus et al.,
PRC 74 (2007)
034903
I. Kraus, J. Cleymans, H. O., K. Redlich, arXiv:0808:0611
Predictions for T = 170 MeV and μB = 1 MeV
Most sensitive particle ratio for RC
Early decision on correlation volume!
STAR nucl-ex.0808.2041
?
Answer is a few months from ALICE!!!
Statistical Hadronization Model:
S = 0 -> no canonical suppression for ϕ
Strangeness undersaturation:
Suppression goes with (γs)ns with nS = 2
News on the ϕ Puzzle
J.H.Chen (STAR) QM2008,nucl-ex0804.4363
S = 2
S =1
ϕ
I. Kraus, et al., Phys.Rev. C76 (2007) 064903
S = 0R = 1
S = 2R as (K/π)2
ϕ/K- is rather constant with √s!
central collisions, heavy systems
Laura‘s talk yesterday, rise due to can. supp of K-
System-size dependence not explained as canonical effect,
if size prop. to Apart .
Cluster concept describes data! As well as γS does.
May be also in very heavy systems clusters,
as R above 2-3 fm grand-canonical behavior.
Cluster size in pp collisions R = 1 – 1.3 fm.
Does R increase with √s?
ϕ/K- always around 0.16, but higher at 1.7 AGeV (0.38±0.13)
In agreement with canonical description with s(ϕ) = 0
The ϕ Puzzle
• At high energies quark content seen,
but the effective strangeness content ?
• At low energies, SHM seems to work,
ignoring the s content of the ϕ but what is its justification?
STAR Coll.,PRL 99 (2007)112301
Partcile Production from SIS to the LHC
J. Cleymans, I. Kraus, H. Oeschler, K. Redlich
Does Hadronization happen via Cluster formation?
Beijing, Oct.7th, 2008
STAR Coll. Phys. Rev. C 71 (2005) 064902
RC is hardly increasing with system size!
What is the strangeness content of the ϕ?
• Data from SPS centrality dependence in PbPb
• System size dependence pp, CC, SiSi
• Data from RHIC AuAu
• New results from 1 – 2 AGeV SIS