Transcript Document
Bulk Properties of QCD – matter at
Highest Colider Energies
Kai Schweda, University of Heidelberg / GSI Darmstadt
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QCD Phase Diagram
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Outline
Identify and study QCD bulk-matter with
partonic degrees of freedom:
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Gobal observable - multiplicity
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Chemical freeze-out, Tch and mB
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Partonic collectivity, Tfo and bT
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Heavy – quark collectivity
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Summary
ISMD, Berkeley, Aug 4 - 9, 2007
Kai Schweda
Mid - rapidity Densities
PHOBOS fit
HIJING BBar
Armesto et al.
AMPT
Eskola
CGC
KLN
ASW
DPMJET-III
EHNRR
at LHC, dN/dh 1000 - 3000
estimate energy density Bj
PHOBOS compilation: W. Busza, SQM07.
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1 1 dET
R 2 0 dy
Theory points: HI at LHC – last call for predictions, CERN, May 2007.
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Kai Schweda
EoS from Lattice QCD
1) Large increase in !
SPS
RHIC
LHC ?
Large increase in Ndof:
Hadrons vs. partons
2) TC ~ 160 MeV
3) Boxes indicate max. initial
temperatures
Longest expansion
duration at LHC
Expect large partonic
collectivity at LHC
Z. Fodor et al, JHEP 0203:014(02)
C.R. Allton et al, hep-lat/0204010
F. Karsch, Nucl. Phys. A698, 199c(02).
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Chemical Freeze - out
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Hadron Yield - Ratios
1) At RHIC:
Tch = 160 ± 10 MeV
mB = 25 ± 5 MeV
2) S = 1.
The hadronic
system is
thermalized at RHIC.
3) Short-lived resonances
show deviations.
There is life after
chemical freeze-out.
RHIC white papers - 2005, Nucl. Phys. A757, STAR: p102; PHENIX: p184;
Statistical Model calculations: P. Braun-Munzinger et al. nucl-th/0304013.
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Kai Schweda
Chemical Freeze-Out vs Energy
With increasing energy:
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Tch increases and saturates
at Tch = 160 MeV
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Coincides with Hagedorn
temperature
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Coincides with early lattice results
limiting temperature for
hadrons, Tch 160 MeV !
mB decreases, mB = 1MeV at LHC
Nearly net-baryon free !
A. Andronic et al., NPA 772 (2006) 167.
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Baryon Ratios
With increasing energy:
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Baryon ratios approach unity
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At LHC, pbar / p 0.95
challenge,
need 1% precision to
address net-baryon
transport !
Compilation: N. Xu
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Partonic Collectivity
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Elliptic Flow
“Elliptic flow is larger for
pions but smaller for
protons at LHC than at
RHIC”.
This is expected
from simple, hydrolike blast-wave fits !
larger collective
flow: mass ordering
more pronounced !
Theory points: C.M. Ko – last call for predictions, CERN, May 2007.
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Collectivity - Energy Dependence
Collectivity parameters <bT>
and <v2> increase with energy
Two extreme secenarios:
(a) Tfo Tch AND bT 0.8
pure partonic
collectivity at LHC!
(b) Tfo Tch , bT 0.3
no collectivity,
no QGP !
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Quark Masses
1)
2)
Higgs mass: electro-weak
symmetry breaking. (current
quark mass)
QCD mass: Chiral symmetry
breaking. (constituent quark
mass)
Strong interactions do not
affect heavy-quark
masses.
Important tool for studying
properties of the hot/dense
medium at RHIC and LHC.
Total quark mass (MeV)
Test pQCD predictions at
RHIC and LHC.
X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu et al., PLB 647 (2007) 366.
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Charm Correlations
c-cbar are correlated
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Pair creation: back to back
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Gluon splitting: forward
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Flavor excitation: flat
Correlations vanish
frequent interactions
among partons !
probe light-quark
thermalization !
Pythia calcs.: G. Tsiledakis.
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Hadronic Re-scattering
Hadronic re-scattering can not completely wash out DD-correlations
Frequent partonic re-scattering needed light quark thermalization !
X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu et al., PLB 647 (2007) 366.
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J/y Production
P. Braun-Munzinger and J. Stachel, Nature 448 (2007) 302.
suppression,
compared to
scaled p+p
(SPS)
regeneration,
enhancement
Low energy (SPS):
few ccbar quarks in the system suppression of J/y
High energy (LHC):
many ccbar pairs in the system enhancement of J/y
Signal of de-confinement + thermalization of light quarks !
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Predictions for LHC
large ccbar production at
LHC
scc
corona effects negligible
regeneration of J/y
dominates
striking centrality
dependence
Signature for QGP
formation !
Initial conditions at LHC ?
A. Andonic et al., nucl-th/0701079.
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Multiply Heavy-flavored Hadrons
Statistical hadronization
- de-confined heavy-quarks
- equilibrated heavy-quarks
Enhancement up to x1000 !
Quarks and gluons hadrons
Pb+Pb
Need total charm yields
c
Wccc / D :
c
Measure Xcc, Wcc, Bc, (Wccc)
x1000
Probe deconfinement and
thermalization @ LHC
c
p+p
QGP !
F. Becattini, Phys. Rev. Lett. 95, 022301 (2005);
P. Braun-Munzinger, K. Redlich, and J. Stachel, nucl-th/0304013.
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Heavy - Quark Production
1)
Charm x 10
2)
Beauty x 100
3) Heavy-quarks abundantly produced at LHC !
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STAR data: A. Suaide, P. Djawothoto QM2006;
Calcs.: R. Vogt.
Kai Schweda
Mid - Rapidity Performance
ATLAS
CMS
Low – momentum
ALICE: large momentum coverage in full azimuth
CMS/ATLAS: Si only tracking
address bulk properties !
CMS: pT > 0.150 GeV
characterize Quark
Gluon Plasma !
CMS: TDR.v2, CERN-LHCC-2007-009; ATLAS: B. Cole, SQM2007; ALICE: PPR.vol.II, J. Phys. G 32 (2006) 1295.
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J/y e+ + e- Reconstruction
J/y: c
c
: b
b
J/y e+ + e identify electrons
through their transition
radiation
Precise
Measurement of
Quarkonia !
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D - Meson Performance
Measure secondary vertex
Direct reconstruction of D0
precise measurement
of total heavy-quark yield
address heavy – quark
collectivity !
ALICE: PPR.vol.II, J. Phys. G 32 (2006) 1295.
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Summary
Bulk properties at LHC:
dN / dh 1000 – 3000
Tch 160 ± 10 MeV, mB 0 – 5 MeV
Tfo Tch all collectivity from partonic stage
<bT> = 0.8 ± 0.05 (c), <v2> 0.08
Measure spectra, correlations and v2 of:
D0, D+, Ds, J/y, Lb,
to identify and characterize QGP !
ALICE is well suited for these studies
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