Physics of Dense Matter ‚ Theoretical Dreams and Hard Facts‘

Phase-Transitions in Nuclear Physics CAP (Coriolis AntiPairing Effect) CAP (Coriolis AntiPairing Effect) Breakdown of overall pairing correlations with spin: Never observed, shadowed by rotational alignment effects, “my biggest hope of seeing a phase transition in nuclei did not materialize” (Ben Mottelson, Physics Nobel Prize 1975). Breakdown of overall pairing correlations with spin: Never observed, shadowed by rotational alignment effects, “my biggest hope of seeing a phase transition in nuclei did not materialize” (Ben Mottelson, Physics Nobel Prize 1975). Liquid-Gas Phase Transition Liquid-Gas Phase Transition Physics of Dense Matter

Transport Trajectories Physics of Dense Matter All trajectories very similar: E-p conservation drives dynamics, not details of phase transition?? Where are the observables for a partonic phase??????

Liquid-Gas Phase Transition Physics of Dense Matter 1975 In finite systems the phase- transition is smeared out around T_c. T_c = 18 MeV in infinite nuclear matter is lowered to about 12 MeV by surface effects and to about 6 – 8 MeV by Coulomb

Liquid-Gas Phase Transition Physics of Dense Matter Caloric Curve (from fragmentation data, 2002): Compatible with LG phase transtion, but also with percolation, critical point only approx. determined. Fragment mass distributions and energy distributions show Thermal behavior

Statics vs. Dynamics Lattice: static properties of idealized state of matter (infinite, at rest, in equilibrium), tremendous progress in last years Lattice: static properties of idealized state of matter (infinite, at rest, in equilibrium), tremendous progress in last years Transport: dynamic treatment of time- evolution of reaction, great progress: off- shell transport, phase transitions attempted Transport: dynamic treatment of time- evolution of reaction, great progress: off- shell transport, phase transitions attempted Thermal model: should emerge as endstage of transport. Why doesn’t it? Thermal model: should emerge as endstage of transport. Why doesn’t it? Fact: Experiment is surely dynamic  how relevant are static calculations? Fact: Experiment is surely dynamic  how relevant are static calculations? Physics of Dense Matter

Ultimate Problems (Over?)-Idealized Theory (LQCD, Effective Field Theories) vs. Real Experiments (non-equilibrium, dynamic, evolution through different phases to final observables). (Over?)-Idealized Theory (LQCD, Effective Field Theories) vs. Real Experiments (non-equilibrium, dynamic, evolution through different phases to final observables). History with LG-phase transition tells us to deemphasize properties of critical point and to concentrate on the proof of a phase transition as such History with LG-phase transition tells us to deemphasize properties of critical point and to concentrate on the proof of a phase transition as such Physics of Dense Matter

The final word N. Bohr : “it appears difficult to define what one should understand by first principles in a field of knowledge where our starting point is empirical evidence of different kinds, which is not directly combinable”. N. Bohr : “it appears difficult to define what one should understand by first principles in a field of knowledge where our starting point is empirical evidence of different kinds, which is not directly combinable”. Physics of Dense Matter