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The Physics of Compressed Nuclear Matter at GSI and FAIR
Mazurian Lakes Conference on Physics 2009Joachim Stroth, Goethe-University / GSI, Germany
Agenda
o Motivationo Recent remarkable results from SIS18o The persepective and challenge at FAIRo Summary
The phase diagram of nuclear matter
Chemical freeze-out points derived from Statistical Hadronization Model Universal conditions for
freeze-out (?) Limiting temperature Tmax? Why is it woking at low beam
energies?
QCD inspired models demonstrate the melting of the condesates.A. Andronic, P. Braun-Munzinger, K. Redlich, J. Stachel
J. Cleymans, K. Redlich
LQCD explores unknown regions from solid grounds at mB=0.
Tc = Tmax? 1st order phase transition Critical point ?
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Schäfer, Wambachpriv. communication
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Schäfer, Wambachpriv. communication
<(qqbar)2>
LeupoldJ.Phys.G32:2199,2006
LHCRHIC
SPSFAIR
SIS
AGS
3fm/GeV6.0
QGP
Hadron gas
F. Karsch et al., Z. Fodor et al.
Ignorant interpretation (Cloudy Bag Model)
qqq
qqq
qqq
qqq
qqq
qqq
qqqq
T Tc , mB ~ 0
qqq
qqq
qqq
qqq
qqq
qqq
qqqq
qq-
qq-qq-
qq-
qq-
qq-
qq-
qq-
qq-Excitation/melting of the vacuum/cloud. smooth cross over
T << Tc , finite mB
qqq
qqq
qqq qqq
qqqqqq
qqq qqq
qq-
T << Tc , finite mB
qqq qqq qqq
qqqqqq
qqq
Bag fusion mixed phase
Phase diagram from large Nc
limitMcLerran, Pisarski: QM09 conjecture for Nc = 3
Quarkyonic Matter: Confined gas of perturbative quarks!
Strange Particle Production at SIS18• HADES,• Ar+KCl at 1.76 GeV/u • FOPI (P. Gasik CPOD 2009),
• Al+Al at 2 GeV/u
Tchem = 70 3 MeV B = 746 15 MeVRC = 2.6 0.4 fm
preliminary
Statistical Model:THERMUS, S. Wheaton and J. Cleymans, hep-ph/0407174Transport:UrQMD, M. Bleicher, S. Vogel at al.
HADES collab.: arXiv:0907.3582 and arXiv:0902.3487
Properties of the Fireball below Ebeam < 30 GeV/u
• Long lifetime of the high-density phase
• Baryon dominated• Extented region of a
strongly interacting hadron gas
1meson
baryon
N
N
Red line from Hadron Gas Model,Sasaki QM09
Dileptons from 1 and 2 GeV/u 12C+12C runs
Phys.
Rev.
Lett
98
(2007
) 05
2302
Phys.
Lett
. B
66
3 (
200
8)
43
Good normalization established in p0 region
Measured pair excess in C+C scales with beam energy as p0 production
What is the contribution from the initial phase?
l+l-
g*
g*
l+l-
g*
l+l -
The solution to the DLS puzzle
C+C collisions compared to NN referenceHADES data agrees with DLS
Electron pairs from Ar+KCl at 1.76 GeV/u
First observation of w mesons in HI collisions at these energies
x 2PLUTO A
Compared to reference after subtraction of contributions from h
•preliminary
• F ~ 3
The Future at GSI and FAIRSIS18Several FOPI runs on strangeness production in 2008 – 2010Upgraded HADES (20 KHz reaction rate) Au+Au and Ag+Ag, pion induced reactions from 2010 on.SIS100:Joint running of HADES and preCBM,multistrange particle and lepton pair excitation function,charm production in proton induced reactionsSIS300:Full exploitation of rare probes a high mB;
fluctuations, flow
Particle multiplicities in detection channel• Au+Au at 25 GeV/u• HSD transport calculation and
statistical hadronization model.
Not fully dressed in HI collisions at AGS and lower SPS energies
The Quest for the Highest Densities
J. Ra
ndru
p an
d J.
Cley
man
s,
hep-
ph/0
6070
65
Freeze-out configurations for X+X collisions in the net-baryon density and energy density plane.
Low-mass vector mesons:what do they tell about chiral symmtery restoration?
Low-mass lepton pairs, …
… the link to the microscopic properties of dense baryonic matter.Special role of the r meson:
– short life time– „photon-like“– coupling to baryons!
xxxxp
dvTd
d
dMdydp
NdcollB
tt
),..(),(),(0
43
oVT ,, 00
isentropic expansion
Thermal dilepton rates
see e.g. R. Rapp, J. Wambach and H. Hees : arXiv:0901.3289,and S. Leupold, U. Mosel and V. Metag arXiv:0907.2388
*,N
h
h
l
l
R.Arnaldi,etal.[NA60collaboration],Phys.Rev.Lett.96,162302(2006)
New approaches in theory
• Hybrid codes for modeling the reaction dynamics
1. Non-equilibrium initial conditions via UrQMD2. Hydrodynamic evolution or transport calculation3. Freeze-out via hadronic cascade (UrQMD)
hydro running time
hydro start time
Pb+Pb, central
(Petersen et al., PRC 78:044901, 2008, arXiv: 0806.1695)
• Introduce virtual photon emissivity from in-medium spectral functions into hydro codes
R. Rapp, H. van Hees, V. Toneev, J. Wambach, B. Friman, Texas A&M, TU Darmstadt, GSI, Giessen, Frankfurt
Ring ImagingCherenkovDetector
Transition Radiation Detectors
Electron identification in CBM
Electron-pair reconstruction in CBM Challenge
- No electron identification before tracking - Background due to material budget of the STS- Sufficient p discrimination (600 p+/-/event, misidentification 10-4)
® Reduction of background by reconstructing pairs fromg-conversion and p0 Dalitz decay via their track topology.
e-
e+
g*p0
g
gp0
g
Track Segment
Track Fragment
Background rejection performance
• Central Au+Au collisions at 25 GeV/u• Free cocktail only (without medium contribution)• Statistic: 200000 events = beam spill on target
All e+e-
Combinatorial bg
Invariant mass spectrumafter all cuts appliedInvariant mass spectrum identified e+e-
Mll > 200 MeV/c2
safetyfactor
;)
NA60 In+In @ 158 AGeVCERES Pb+Au @ 40 AGeVCERES Pb+Au @ 158 AGeV (σ/σtot = 28%)CERES Pb+Au @ 158 AGeV (σ/σtot = 7%)CERES Pb+Au @ 158 AGeV PHENIX Au+Au @ √s = 200 AGeV
Comparison of expected performance to existing dilepton experiments
Charmonium suppression.
c c-
The Charm of CBM
Rare but measurement feasible!– Very sparse experimental
information– At threshold, production
mechanism in pA and AA unclear.
Open charm in CBMBR M / 1012 events1)
4 10-5 56000
1 10-4 174000
9 10-5 195000
4 10-5 103000
1012 events 40 weeks running at 105 interaction rate.Event selection: Real-time vertex finding in 20 Gbyte data/s.
KD0
KD 0
KD
KD
W. Cassing, E.L. Bratkovskaya, and A. Sibirtsev,Nucl.Phys.A691,753(2001)
Charm propagation
How are the produced charm quarks propagating in the dense phase, quark like or (pre-)hadron like ?
– Charmonium over open charm as indicator!– Charmed baryons important for a complete picture.– Are there indications of collectivity.
O. Linnyk, E. Bratkovskaya and W. Cassing, arXiv:0808.1504v1A. Andronic, P. Braun-Munzinger, et al., Phys. Lett. B 659 (2007) 149, arXiv:0708.1488
Summary
– „Long-lived“ states of dense nuclear matter are produced in collisions of heavy ion at energies of a few GeV/u.
– The phase in the high-density region might be much more exotic then a hadron/resonance gas.
– Unfortunately, there is no smoking gun, but:• Fast equillibration• „Sub-threshold“ production• Strong broadening of in-medium states
– Close collaboration with, and novel approaches in theory are necessary to make the case.