Jan Rafelski

Evidence for a phase with high specific entropy in nuclear collisions

We determine the entropy per baryon content of the central reaction region in terms of the charged particle multiplicity. We study the consistency of our findings with recent data on strange anti-baryon production at 200 GeV A in S→A collisions (A∼200) assuming formation of a central fireball. Hadron gas models which do not invoke strong medium modifications of hadron masses do not provide enough entropy and are inconsistent with the combined experimental results. In contrast the quark-gluon plasma hypothesis explains them naturally. PACS 25.75.+r, 12.38.Mh Published in Phys. Rev. Letters 70 (1993) 3530–3533. PAR/LPTHE/92–37 TPR-92-39 AZPH-TH/92-30 September 30, 1992 Work supported by DFG, BMFT, GSI, and NATO, grant CRG 910991 Work supported by DOE, grant DE-FG02-92ER 40733, and NATO, grant CRG 910991 Unité associée au CNRS

STRANGENESS AND PARTICLE FREEZE-OUT IN NUCLEAR COLLISIONS AT 14.6 GeV A

Abstract We study the chemical conditions at freeze-out associated with the production of strange-particles in SiAu collisions at 14.6 GeV A. We obtain freeze-out chemical potentials and temperature, and determine the entropy as well as the final particle abundance. We also consider in detail the alternative evolution scenarios involving the hadronic gas and the deconfined phase.

FROM QUARK-GLUON UNIVERSE TO NEUTRINO DECOUPLING: 200 < T < 2 MeV

The properties of the quark and hadron Universe are explored. Kinetic theory considerations are presented proving that hadron abundances after phase transformation from quarks to hadrons remain intact till abundances of hadrons become irrelevant. The hadronization process and the evolution of hadron yields are described in detail.

Compact ultra dense objects in the solar system

We describe properties and gravitational interactions of meteor-mass and greater compact ultra dense objects with nuclear density or greater (CUDO s). We discuss possible enclosure of CUDO s in comets, stability of these objects on impact with the Earth and Sun and show that the hypothesis of a CUDO core helps resolve issues challenging the understanding of a few selected cometary impacts.

Dynamics of multiparticle systems with non–abelian symmetry

Abstract. We consider the dynamics governing the evolution of a many body system constrained by a nonabelian local symmetry. We obtain explicit forms of the global macroscopic condition assuring that at the microscopic level the evolution respects the overall symmetry constraint. We demonstrate the constraint mechanisms for the case of SU(2) system comprising particles in fundamental, and adjoint representations (‘nucleons’ and ‘pions’).

Magnetic permeability in constrained fermionic vacuum

Abstract We obtain using Schwingers proper time approach the Casimir-Euler-Heisenberg effective action of fermion fluctuations for the case of an applied magnetic field. We implement here the compactification of one space dimension into a circle through anti-periodic boundary condition. Aside of higher order non-linear field effects we identify a novel contribution to the vacuum permeability. These contributions are exceedingly small for normal electromagnetism due to the smallness of the electron Compton wavelength compared to the size of the compactified dimension, if we take the latter as the typical size of laboratory cavities, but their presence is thought provoking, also considering the context of strong interactions.

Strangeness in QGP: Hadronization pressure

We review strangeness as signature of quark gluon plasma (QGP) and the hadronization process of a QGP fireball formed in relativistic heavy-ion collisions in the entire range of today accessible reaction energies. We discuss energy dependence of the statistical hadronization parameters within the context of fast QGP hadronization. We find that QGP breakup occurs for all energies at the universal hadronization pressure

Nonlinear electromagnetic forces in astrophysics

P = 80\pm 3\,\mathrm{MeV/fm}^3

Planetary Impacts by Clustered Quark Matter Strangelets

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Strangeness and Quark--Gluon Plasma

Electromagnetism becomes a nonlinear theory having (effective) photon-photon interactions due at least to electron-positron fluctuations in the vacuum. We discuss the consequences of the nonlinearity for the force felt by a charge probe particle, and compare the impact of Euler-Kockel QED effective nonlinearity to the possibility of Born-Infeld-type nonlinearity.