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The Physics of Dense Nuclear Matter

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Presentation on theme: "The Physics of Dense Nuclear Matter"— Presentation transcript:

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 mesons
K- 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

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