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Phase transition to hyperon matter in neutron stars (2002)

Jürgen Schaffner-Bielich Matthias Hanauske Horst Stöcker Walter Greiner

Recent progress in the understanding of the high density phase of neutron stars advances the view that a substantial fraction of the matter consists of hyperons. The possible impacts of a highly attractive interaction between hyperons on the properties of compact stars are investigated. We find that a hadronic equation of state with hyperons allows for a first order phase transition to hyperonic matter. The corresponding hyperon stars can have rather small radii of R ~ 8 km. PACS: 26.60+c, 21.65+f, 97.60.Gb, 97.60.Jd

Space-time evolution and HBT analysis of relativistic heavy ion collisions in a chiral SU(3) x SU(3) model (2002)

Detlef Zschiesche Stefan Schramm Horst Stöcker Walter Greiner

The space-time dynamics and pion-HBT radii in central heavy ion-collisions at CERN-SPS and BNL-RHIC are investigated within a hydrodynamic simulation. The dependence of the dynamics and the HBT-parameters on the EoS is studied with different parametrizations of a chiral SU(3) sigma omega model. The selfconsistent collective expansion includes the e ects of e ective hadron masses, generated by the nonstrange and strange scalar condensates. Different chiral EoS show di erent types of phase transitions and even a crossover. The influence of the order of the phase transition and of the latent heat on the space-time dynamics and pion-HBT radii is studied. A small latent heat, i.e. a weak first-order chiral phase transition, or a smooth crossover lead to distinctly di erent HBT predictions than a strong first order phase transition. A quantitative description of the data, both at SPS energies as well as at RHIC energies, appears di cult to achieve within the ideal hydrodynamic approach using the SU(3) chiral EoS. A strong first-order quasi-adiabatic chiral phase transition seems to be disfavored by the pion-HBT data from CERN-SPS and BNL-RHIC.

Quasi-stable black holes at the large hadron collider (2002)

Sabine Hossenfelder Stefan Hofmann Marcus Bleicher Horst Stöcker

We address the production of black holes at LHC and their time evolution in space times with compactified space like extra dimensions. It is shown that black holes with life times of several hundred fm/c can be produced at LHC. The possibility of quasi-stable remnants is discussed.

Kinetic equation for gluons in the background gauge of QCD (2002)

Qun Wang Krzysztof Redlich Horst Stöcker Walter Greiner

We derive the quantum kinetic equation for a pure gluon plasma, applying the background field and closed-time-path method. The derivation is more general and transparent than earlier works. A term in the equation is found which, as in the classical case, corresponds to the color charge precession for partons moving in the gauge field. PACS numbers: 12.38.Mh, 25.75.-q, 24.85.+p, 11.15.Kc

Suppression of high-P T jets as a signal for large extra dimensions and new estimates of lifetimes for meta stable micro black holes : from the early universe to future colliders (2002)

Stefan Hofmann Marcus Bleicher Lars Gerland Sabine Hossenfelder Sascha Schwabe Horst Stöcker

We address the production of black holes at LHC in space times with compactified space-like large extra dimensions (LXD). Final state black hole production leads to suppression of high-PT jets, i.e. a sharp cut-o in (pp!jet+X). This signal is compared to the jet plus missing energy signature due to graviton production in the final state as proposed by the ATLAS collaboration. Time evolution and lifetimes of the newly created black holes are calculated based on the micro- canonical formalism. It is demonstrated that previous lifetime estimates of micro black holes have been dramatically underestimated. The creation of a large number of quasi-stable black holes is predicted with life times of hundred fm/c at LHC. Medium modifications of the black holes evaporation rate due to the quark gluon plasma in relativistic heavy ion collisions as well as provided by the cosmic fluid in the early universe are studied

Black hole production in large extra dimensions at the Tevatron : possibility for a first glimpse on TeV scale gravity (2002)

Marcus Bleicher Stefan Hofmann Sabine Hossenfelder Horst Stöcker

The production of black holes in large extra dimensions is studied for Tevatron energies. We find that black holes may have already been created in small abundance in pp collisions at ps = 1.8 TeV. For the next Tevatron run (ps = 2.0 TeV) large production rates for black holes are predicted.

Bound states of anti-nucleons in finite nuclei (2002)

Guangjun Mao Horst Stöcker Walter Greiner

We study the bound states of anti-nucleons emerging from the lower continuum in finite nuclei within the relativistic Hartree approach including the contributions of the Dirac sea to the source terms of the meson fields. The Dirac equation is reduced to two Schr¨odinger-equivalent equations for the nucleon and the anti-nucleon respectively. These two equations are solved simultaneously in an iteration procedure. Numerical results show that the bound levels of anti-nucleons vary drastically when the vacuum contributions are taken into account. PACS number(s): 21.10.-k; 21.60.-n; 03.65.Pm

Phase transition to hyperon matter in neutron stars (2002)

Jürgen Schaffner-Bielich Matthias Hanauske Horst Stöcker Walter Greiner

Recent progress in the understanding of the high density phase of neutron stars advances the view that a substantial fraction of the matter consists of hyperons. The possible impacts of a highly attractive interaction between hyperons on the properties of compact stars are investigated.We find that a hadronic equation of state with hyperons allows for a first order phase transition to hyperonic matter. The corresponding hyperon stars can have rather small radii of R 8 km.

Open and hidden charm production in heavy-ion collisions at ultrarelativistic energies (2002)

Mark I. Gorenstein Andriy P. Kostyuk Larry McLerran Horst Stöcker Walter Greiner

We consider the production of the open charm and J/psi mesons in heavy-ion collisions at BNL RHIC. We discuss several recently developed pictures for J/psi production and argue that a measurement at RHIC energies is crucial for disentangling these different descriptions.

Tevatron - probing TeV-scale gravity today (2002)

Stefan Hofmann Marcus Bleicher Lars Gerland Sabine Hossenfelder Kerstin Paech Horst Stöcker

The production of black holes at Tevatron and LHC in spacetimes with compactified space-like large extra dimensions is studied. Either black holes can already be observed in ¯ pp collisions at s = 1.8 TeV or the fundamental gravity scale has to be above 1.4 TeV. At LHC the creation of a large number of quasi-stable black holes is predicted, with lifetimes beyond several hundred fm/c. A cut-off in the high-PT jet cross section is shown to be a unique signature of black hole production. This signal is compared to the jet plus missing energy signature due to graviton production in the final state as proposed by the ATLAS collaboration.

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