1. The Physics of Dense Nuclear Matter
Introduction
Status Near future
Perspectives at FAIR
Joachim Stroth
Univ. Frankfurt / GSI

2. Dense nuclear matter in the laboratory
What are the properties of dense nuclear matter?
Dense matter
Freeze-out
First chance collisions
Its macroscopic properties depend on the microscopic structure!
→ Hadron physics (in-medium)
NuPPEC meeting, Paris, November 2004
Joachim Stroth

3. The physics case
Does the quark model provide the right description of hadrons?
What is the relevant excitation spectrum as the matter density increases?
What is the role of chiral symmetry breaking in the generation of hadron masses?
Where are the limits of hadronic existence?
J. Wambach et al.
Matter properties (EOS) of compact stars!
By detecting lepton pairs, we would like to study the electromagnetic structure of dense nuclear matter in the time-like region. Addressed questions in this field are those listed here:
You all know, that hadron properties do change while hadrons are subjected to a medium. In some cases, if you like, they are starting to dissolve, other broad resonance structure (like the sigma) might narrow done.
Two main features are made responsible for such effects:
1. non-perturbative QCD tells us, that in vacuum chiral symmetry is spontaneously broken. The order parameter for the breaking is the chiral condensate. Model calculations show that this condensate depletes while matter density increases. It is conjectured that in consequence hadron masses will change.
2. Secondly, once a hadron is surrounded by others, additional self-energy terms will modify its spectral function.
To study changes of hadron properties in different reactions is the objective of the HADES project.
NuPPEC meeting, Paris, November 2004
Joachim Stroth

4. Nava, GSI, Munich, Jülich, Tokyo, Niigata, RIKEN
Pionic atoms
Fragment separator at GSI used as high-resolution forward spectrometer
Collaboration
Nava, GSI, Munich, Jülich, Tokyo, Niigata, RIKEN
Mesonic Atoms
Experiments combine techniques from hadron and heavy ion physics. (inelastic NN reaction and pick-up).
Pions with favorable momentum are trapped in the Coulomb-field of the heavy Nucleus.
Pionic bound states are clearly observed.
The measured binding energies evidence a reduced expectation value of the Chiral Condensate at nuclear ground state density.
NuPPEC meeting, Paris, November 2004
Joachim Stroth

5. In-medium mass of strange mesonsK- K+
KAOS results selected among the 10 most important physics results in 1998 (APS)
AGeV central collisions
M. Menzel et al., KaoS Collab., Phys. Lett. B 495 (2000) 26
K. Wisniewski et al., FOPI Collab., Eur. Phys. J A 9 (2000) 515 Transport calculations: G.Q. Li & G.E. Brown
In-medium potential of strange mesons should lead to shift a of the effective kaon mass!
Indication observed in heavy ion reaction at the SIS18, GSI by KAOS and FOPI.
NuPPEC meeting, Paris, November 2004
Joachim Stroth

6. Kaonic bound states Exotic bound states with strangeness
Attractive K- N potential results in additional binding
Production mechanisms presently uncertain, might be populated in HI collisions but probably also in p induced reactions.
NuPPEC meeting, Paris, November 2004
Joachim Stroth

7. HADES High Acceptance Dielectron Spectrometer
Beams of:
Pions
Protons
Nuclei
preliminary
12C+ 12C 2 AGeV  e+ e-
208Pb - n
Low-mass vector mesons
Detected by electron pair reconstruction (penetrating probes).
Spectrometer with high invariant mass resolution and high rate capability.
operational since 2001 at GSI.
NuPPEC meeting, Paris, November 2004
Joachim Stroth

8. Storage and Cooler Rings
International FAIR Project: SIS300
Key Technical Features
Cooled beams
Rapidly cycling superconducting magnets
Primary Beams
1012/spill; GeV/u; 238U28+
Factor over present in intensity
2(4)x1013/spill 30 GeV protons
1010/spill 238U73+ up to 35 GeV/u
up to 90 GeV protons
SIS 100/300
Secondary Beams
SIS
UNILAC
Broad range of radioactive beams up to GeV/u; up to factor in intensity over present
Antiprotons GeV
CBM
Storage and Cooler Rings
Radioactive beams
e- – A (or Antiproton-A) collider
stored and cooled GeV antiprotons
NuPPEC meeting, Paris, November 2004
Joachim Stroth

9. The energy scan at SPS (NA94)
Exiting observations at an energy of around 30 AGeV
Relative enhancement of strangeness
Not explained by transport calculations and statistical model
SPS heavy ion program suspended due to priority for LHC
CERN SPS-C:
"The search for the critical point is of high importance for the understanding of QCD Respective proposals can be accepted for a time period after 2008". Integrated Luminosity ?
NA49, M. Gazdzicki et al.
Fluctuations due to approach of the critical point ??
NuPPEC meeting, Paris, November 2004
Joachim Stroth

10. The Compressed Baryonic Matter program
Experimental goal of the CBM collaboration:
Systematic investigation of
dense baryonic matter using
penetrating and rare probes!
Heavy ion collisions at interaction rates of up to 107 Hz
Excitation functions from 2 to 35 GeV/u
Needs large integrated luminosity:
High beam intensity and duty cycle,
available for several month per year
CBM Detector
HADES
Observables:
Penetrating probes: , , , J/
Strangeness: K, , , , ,
Open charm: Do, D
Hadrons ( p, π), exotica
NuPPEC meeting, Paris, November 2004
Joachim Stroth

11. Physics program of CBM Fluctuations in the strangeness production
Signal for the critical point
Low mass electron pairs
Probe the in-medium structure of hadrons
Near threshold open-charm production
Analogy to strangeness at AGeV
Charmonium production
Sensitive to the early state of the matter
SIS18
SIS300
NuPPEC meeting, Paris, November 2004
Joachim Stroth

12. The physics community
FOPI upgrade → heavy ion program world-wide unique
European collaboration + Japan: 50 physicist
Bucharest, Budapest, Clermont-Ferrand, Darmstadt, Dresden, Florence, Heidelberg, Moscow, Seoul, Strasbourg, Warszawa, Zagreb
HADES → heavy ions world-wide unique (elementary JLAB, KEK)
European collaboration: 120 physicist
Bratislava, Catania, Dubna, Frankfurt, Giessen, Milano, Moscow, Garching, Nicosia, Orsay, Rez, Dresden, Santiago de Compostela, Valencia
CBM → RHIC low energy program uncertain, SPS suspended
International collaboration: >300 physicist Further interest by people from former NA49 experiment – CERN proposal ?
Theory → Microscopic transport essential
Smaller groups at different universities
FP6 I3HP
Let me finish with some general remarks. All these projects are realized in truly international collaborations. As you can see, scientist from 22 institution and 12 countries have signed up for CBM. It is evident that not only the scientific horizon is opened.
But the collaborations also span between large facilities and universities. The many students profit from that and can be educated and trained in a very pragmatic way in a broad spectrum of frontline technology.
FP6 I3HP
FP6 I3HP
NuPPEC meeting, Paris, November 2004
Joachim Stroth

13. Motivation: II
„The challenge for the next century physics is: explain confinement and broken (chiral) symmetry“ T.D. Lee
„But perhaps the most interesting and surprising thing about QCD at high density is that, by thinking about it, one discovers a fruitful new perspective on the traditional problem of confinement and chiral-symmetry breaking”. F. Wilczek
NuPPEC meeting, Paris, November 2004
Joachim Stroth

14. NuPPEC meeting, Paris, November 2004
Joachim Stroth