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Thu, 22 Jan 2015 13:39:28 +0100Thu, 22 Jan 2015 13:39:28 +0100QCD equation of state from a chiral hadronic model including quark degrees of freedom
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/34819
This work presents an effective model for strongly interacting matter and the QCD equation of state (EoS). The model includes both hadron and quark degrees of freedom and takes into account the transition of chiral symmetry restoration as well as the deconfinement phase transition. At low temperatures T and baryonic densities ρB a hadron resonance gas is described using a SU(3)-flavor sigma-omega model and a quark phase is introduced in analogy to PNJL models for higher T and ρB. In this way, the correct asymptotic degrees of freedom are used in a wide range of T and ρB. Here, results of this model concerning the chiral and deconfinement phase transitions and thermodynamic model properties are presented. Large hadron resonance multiplicities in the transition region emphasize the importance of heavy-mass resonance states in this region and their impact on the chiral transition behavior. The resulting phase diagram of QCD matter at small chemical potentials is in line with latest lattice QCD and thermal model results.Philip Rau; Jan Steinheimer; Stefan Schramm; Horst Stöckerconferenceobjecthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/34819Thu, 22 Jan 2015 13:39:28 +0100Nanolesions induced by heavy ions in human tissues: experimental and theoretical studies
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/27776
The biological effects of energetic heavy ions are attracting increasing interest for their applications in cancer therapy and protection against space radiation. The cascade of events leading to cell death or late effects starts from stochastic energy deposition on the nanometer scale and the corresponding lesions in biological molecules, primarily DNA. We have developed experimental techniques to visualize DNA nanolesions induced by heavy ions. Nanolesions appear in cells as “streaks” which can be visualized by using different DNA repair markers. We have studied the kinetics of repair of these “streaks” also with respect to the chromatin conformation. Initial steps in the modeling of the energy deposition patterns at the micrometer and nanometer scale were made with MCHIT and TRAX models, respectively.Marcus Bleicher; Lucas Burigo; Marco Durante; Maren Herrlitz; Michael Krämer; Igor Mishustin; Iris Müller; Francesco Natale; Igor Pshenichnov; Stefan Schramm; Gisela Taucher-Scholz; Cathrin Wälzleinarticlehttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/27776Thu, 13 Dec 2012 16:28:23 +0100Hybrid approaches to heavy ion collisions and future perspectives
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/16727
We present the current status of hybrid approaches to describe heavy ion collisions and their future challenges and perspectives. First we present a hybrid model combining a Boltzmann transport model of hadronic degrees of freedom in the initial and final state with an optional hydrodynamic evolution during the dense and hot phase. Second, we present a recent extension of the hydrodynamical model to include fluctuations near the phase transition by coupling a chiral field to the hydrodynamic evolution.Marlene Nahrgang; Christoph Herold; Stefan Schramm; Marcus Bleicherarticlehttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/16727Fri, 29 Apr 2011 15:51:23 +0200Structure of the vacuum in nuclear matter: a nonperturbative approach
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/2383
We compute the vacuum polarization correction to the binding energy of nuclear matter in the Walecka model using a nonperturbative approach. We first study such a contribution as arising from a ground-state structure with baryon-antibaryon condensates. This yields the same results as obtained through the relativistic Hartree approximation of summing tadpole diagrams for the baryon propagator. Such a vacuum is then generalized to include quantum effects from meson fields through scalar-meson condensates which amounts to summing over a class of multiloop diagrams. The method is applied to study properties of nuclear matter and leads to a softer equation of state giving a lower value of the incompressibility than would be reached without quantum effects. The density-dependent effective sigma mass is also calculated including such vacuum polarization effects.Amruta Mishra; P. K. Panda; Stefan Schramm; Joachim Reinhardt; Walter Greinerarticlehttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/2383Fri, 14 Jul 2006 10:15:51 +0200Coulomb effects on electromagnetic pair production in ultrarelativistic heavy-ion collisions
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/2391
We calculate the asymptotic high-energy amplitude for electrons scattering at one ion, as well as at two colliding ions, by means of perturbation theory. We show that the interaction with one ion eikonalizes and that the interaction with two ions causally decouples. We are able to put previous results on perturbative grounds and propose further applications for the obtained rules for interactions on the light cone. We discuss the implications of the eikonal amplitude on the pair production probability in ultrarelativistic peripheral heavy-ion collisions. In this context the Weizsäcker-Williams method is shown to be exact in the ultrarelativistic limit, irrespective of the produced particles’ mass. A new equivalent single-photon distribution is derived, which correctly accounts for Coulomb distortions. The impact on single-photon induced processes is discussed.U. Eichmann; Joachim Reinhardt; Stefan Schramm; Walter Greinerarticlehttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/2391Fri, 14 Jul 2006 10:12:20 +0200Phase transition in the chiral sigma-omega model with dilatons
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3002
We investigate the properties of di erent modifications to the linear -model (including a dilaton field associated with broken scale invariance) at finite baryon density and nonzero temperature T. The explicit breaking of chiral symmetry and the way the vector meson mass is generated are significant for the appearance of a phase of nearly vanishing nucleon mass besides the solution describing normal nuclear matter. The elimination of the abnormal solution prohibits the onset of a chiral phase transition but allows to lower the compressibility to a reasonable range. The repulsive contributions from the vector mesons are responsible for the wide range of stability of the normal phase in the (µ, T)-plane. The abnormal solution becomes not only energet- ically preferable to the normal state at high temperature or density, but also mechanically stable due to the inclusion of dilatons. PACS number:12.39.FPanajotis Papazoglou; Jürgen Schaffner; Stefan Schramm; Detlef Zschiesche; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3002Thu, 19 Jan 2006 14:26:55 +0100Chiral Lagrangian for strange hadronic matter
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3039
A generalized Lagrangian for the description of hadronic matter based on the linear SU(3)L × SU(3)R -model is proposed. Besides the baryon octet, the spin-0 and spin-1 nonets, a gluon condensate associated with broken scale invariance is incorporated. The observed values for the vacuum masses of the baryons and mesons are reproduced. In mean-field approximation, vector and scalar interactions yield a saturating nuclear equation of state. We discuss the di culties and possibilities to construct a chiral invariant baryon-meson interaction that leads to a realistic equation of state. It is found that a coupling of the strange condensate to nucleons is needed to describe the hyperon potentials correctly. The effective baryon masses and the appearance of an abnormal phase of nearly massless nucleons at high densities are examined. A nonlinear realization of chiral symmetry is considered, to retain a Yukawa-type baryon-meson interaction and to establish a connection to the Walecka-model.Panajotis Papazoglou; Stefan Schramm; Jürgen Schaffner-Bielich; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3039Thu, 05 Jan 2006 09:34:39 +0100Hypermatter in chiral field theory
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3038
Abstract. A generalized Lagrangian for the description of hadronic matter based on the linear SU(3)L × SU(3)R -model is proposed. Besides the baryon octet, the spin-0 and spin-1 nonets, a gluon condensate associated with broken scale invariance is incorporated. The observed values for the vacuum masses of the baryons and mesons are reproduced. In mean-field approximation, vector and scalar interactions yield a saturating nuclear equation of state. Finite nuclei can be reasonably described, too. The condensates and the e ective baryon masses at finite baryon density and temperature are discussed.Panajotis Papazoglou; Detlef Zschiesche; Stefan Schramm; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3038Thu, 05 Jan 2006 09:33:08 +0100Nuclei in a chiral SU(3) model
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3099
Nuclei can be described satisfactorily in a nonlinear chiral SU(3)-framework, even with standard potentials of the linearmodel. The condensate value of the strange scalar meson is found to be important for the properties of nuclei even without adding hyperons. By neglecting terms which couple the strange to the nonstrange condensate one can reduce the model to a Walecka model structure embedded in SU(3). We discuss inherent problems with chiral SU(3) models regarding hyperon optical potentials.Panajotis Papazoglou; Detlef Zschiesche; Stefan Schramm; Jürgen Schaffner-Bielich; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3099Mon, 12 Dec 2005 10:29:16 +0100Kaon effective mass and energy from a novel chiral SU(3) symmetric Lagrangian
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3098
A new chiral SU(3) Lagrangian is proposed to describe the properties of kaons and antikaons in the nuclear medium, the ground state of dense matter and the kaon-nuclear interactions consistently. The saturation properties of nuclear matter are reproduced as well as the results of the Dirac-Brückner theory. After taking into account the coupling between the omega meson and the kaon, we obtain similar results for the e ective kaon and antikaon energies as calculated in the one-boson-exchange model while in our model the parameters of the kaon-nuclear interactions are constrained by the SU(3) chiral symmetry. PACS number(s): 14.40.Aq, 12.39.Fe, 21.30.FeGuangjun Mao; Panajotis Papazoglou; Stefan Hofmann; Stefan Schramm; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3098Mon, 12 Dec 2005 10:10:27 +0100Effective kaon energy from a novel chiral SU(3) model
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3113
A new chiral SU(3) Lagrangian is proposed to describe the properties of kaons and anti-kaons in the nuclear medium. The saturation properties of nuclear matter are reproduced as well as the results of the Dirac-Brückner theory. After introducing the coupling between the omega meson and the kaon, our results for e ective kaon and anti-kaon energy are quite similar as calculated in the one-boson-exchange model.Guangjun Mao; Panajotis Papazoglou; Stefan Hofmann; Stefan Schramm; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3113Thu, 08 Dec 2005 11:13:50 +0100Chiral model for dense, hot and strange hadronic matter
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3145
Introduction: Until now it is not possible to determine the equation of state (EOS) of hadronic matter from QCD. One succesfully applied alternative way to describe the hadronic world at high densities and temperatures are effective models like the RMF-models [1], where the relevant degrees of freedom are baryons and mesons instead of quarks and gluons. Since approximate chiral symmetry is an essential feature of QCD, it should be a useful concept for building and restricting e ective models. It has been shown [2,3] that effective sigma-omega models including SU(2) chiral symmetry are able to obtain a reasonable description of nuclear matter and finite nuclei. Recently [4] we have shown that an extended SU(3) × SU(3) chiral sigma-omega model is able to describe nuclear matter ground state properties, vacuum properties and finite nuclei satisfactorily. This model includes the lowest SU(3) multiplets of the baryons (octet and decuplet[5]), the spin-0 and the spin-1 mesons as the relevant degrees of freedom. Here we will discuss the predictions of this model for dense, hot, and strange hadronic matter.Detlef Zschiesche; Panajotis Papazoglou; Christian W. Beckmann; Stefan Schramm; Jürgen Schaffner-Bielich; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3145Tue, 29 Nov 2005 10:40:12 +0100Neutron star properties in a chiral SU(3) model
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3153
We investigate various properties of neutron star matter within an e ective chiral SU(3)L × SU(3)R model. The predictions of this model are compared with a Walecka-type model. It is demonstrated that the importance of hy- peron degrees are strongly depending on the interaction used, even if the equation of state near saturation density is nearly the same in both models. While the Walecka-type model predicts a strange star core with strangeness fraction fS 4/3, the chiral model allows only for fS 1/3 and predicts that 0, + and 0 will not exist in star, in contrast to the Walecka-type model. PACS: 26.60+c, 21.65+f, 24.10JvMatthias Hanauske; Detlef Zschiesche; Subrata Pal; Stefan Schramm; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3153Thu, 24 Nov 2005 10:44:38 +0100Hadrons in dense resonance matter: a chiral SU(3) approach
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3184
A nonlinear chiral SU(3) approach including the spin 3 2 decuplet is developed to describe dense matter. The coupling constants of the baryon resonances to the scalar mesons are determined from the decuplet vacuum masses and SU(3) symmetry relations. Di erent methods of mass generation show significant differences in the properties of the spin- 3 2 particles and in the nuclear equation of stateDetlef Zschiesche; Panajotis Papazoglou; Stefan Schramm; Jürgen Schaffner-Bielich; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3184Wed, 23 Nov 2005 11:28:55 +0100Superheavy nuclei in a chiral hadronic model
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3182
Superheavy nuclei are investigated in a nonlinear chiral SU(3)-model. The proton number Z=120 and neutron numbers of N=172, 184 and 198 are predicted to be magic. The charge distributions and alpha-decay chains hint towards a hollow stucture.Christian Beckmann; Panajotis Papazoglou; Detlef Zschiesche; Stefan Schramm; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3182Wed, 23 Nov 2005 10:13:43 +0100Critical review of quark gluon plasma signals
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3186
Compelling evidence for a new form of matter has been claimed to be formed in Pb+Pb collisions at SPS. We critically review two suggested signatures for this new state of matter: First the suppression of the J/psi , which should be strongly suppressed in the QGP by two different mechanisms, the color-screening [1] and the QCD-photoe ect [2]. Secondly the measured particle, in particular strange hadronic, ratios might signal the freeze-out from a quark-gluon phase.Detlef Zschiesche; Lars Gerland; Stefan Schramm; Jürgen Schaffner-Bielich; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3186Wed, 23 Nov 2005 09:19:04 +0100Nuclei, superheavy nuclei, and hypermatter in a chiral SU(3) model
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3259
A model based on chiral SU(3)-symmetry in nonlinear realisation is used for the investigation of nuclei, superheavy nuclei, hypernuclei and multistrange nuclear objects (so called MEMOs). The model works very well in the case of nuclei and hypernuclei with one Lambda-particle and rules out MEMOs. Basic observables which are known for nuclei and hypernuclei are reproduced satisfactorily. The model predicts Z=120 and N=172, 184 and 198 as the next shell closures in the region of superheavy nuclei. The calculations have been performed in self-consistent relativistic mean field approximation assuming spherical symmetry. The parameters were adapted to known nuclei.Christian Beckmann; Panajotis Papazoglou; Detlef Zschiesche; Stefan Schramm; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3259Thu, 17 Nov 2005 13:07:00 +0100Space-time evolution and HBT analysis of relativistic heavy ion collisions in a chiral SU(3) x SU(3) model
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3264
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.Detlef Zschiesche; Stefan Schramm; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3264Thu, 17 Nov 2005 11:02:36 +0100Particle ratios at RHIC : effective hadron masses and chemical freeze-out
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3288
The measured particle ratios in central heavy-ion collisions at RHIC-BNL are investigated within a chemical and thermal equilibrium chiral SU(3) theta - omega approach. The commonly adopted noninteracting gas calculations yield temperatures close to or above the critical temperature for the chiral phase transition, but without taking into account any interactions. Contrary, the chiral SU(3) model predicts temperature and density dependent e ective hadron masses and e ective chemical potentials in the medium and a transition to a chirally restored phase at high temperatures or chemical potentials. Three di erent parametrizations of the model, which show di erent types of phase transition behaviour, are investigated. We show that if a chiral phase transition occured in those collisions, freezing of the relative hadron abundances in the symmetric phase is excluded by the data. Therefore, either very rapid chemical equilibration must occur in the broken phase, or the measured hadron ratios are the outcome of the dynamical symmetry breaking. Furthermore, the extracted chemical freeze-out parameters di er considerably from those obtained in simple noninteracting gas calculations. In particular, the three models yield up to 35 MeV lower temperatures than the free gas approximation. The in-medium masses turn out di er up to 150 MeV from their vacuum values.Detlef Zschiesche; Stefan Schramm; Jürgen Schaffner-Bielich; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3288Tue, 15 Nov 2005 11:49:54 +0100In-medium vector meson masses in a chiral SU(3) model
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3303
A significant drop of the vector meson masses in nuclear matter is observed in a chiral SU(3) model due to the e ects of the baryon Dirac sea. This is taken into account through the summation of baryonic tadpole diagrams in the relativistic Hartree approximation. The appreciable decrease of the in-medium vector meson masses is due to the vacuum polarisation e ects from the nucleon sector and is not observed in the mean field approximation.Detlef Zschiesche; Amruta Mishra; Stefan Schramm; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3303Mon, 14 Nov 2005 10:38:37 +0100Mass modification of D-meson in hot hadronic matter
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3324
We evaluate the in-medium D and -meson masses in hot hadronic matter induced by interactions with the light hadron sector described in a chiral SU(3) model. The e ective Lagrangian approach is generalized to SU(4) to include charmed mesons. We find that the D-mass drops substantially at finite temperatures and densities, which open the channels of the decay of the charmonium states ( 2, c, J/ ) to D pairs in the thermal medium. The e ects of vacuum polarisations from the baryon sector on the medium modification of the D-meson mass relative to those obtained in the mean field approximation are investigated. The results of the present work are compared to calculations based on the QCD sum-rule approach, the quark-meson coupling model, chiral perturbation theory, as well as to studies of quarkonium dissociation using heavy quark potential from lattice QCD.Amruta Mishra; Elena L. Bratkovskaya; Jürgen Schaffner-Bielich; Stefan Schramm; Horst Stöckerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3324Thu, 10 Nov 2005 10:34:59 +0100Effects of Dirac sea polarization on hadronic properties : a Chiral SU(3) approach
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3325
Abstract: The e ect of vacuum fluctuations on the in-medium hadronic properties is investigated using a chiral SU(3) model in the nonlinear realization. The e ect of the baryon Dirac sea is seen to modify hadronic properties and in contrast to a calculation in mean field approximation it is seen to give rise to a significant drop of the vector meson masses in hot and dense matter. This e ect is taken into account through the summation of baryonic tadpole diagrams in the relativistic Hartree approximation (RHA), where the baryon self energy is modified due to interactions with both the non-strange ( ) and the strange ( ) scalar fields.Amruta Mishra; K. Balazs; Detlef Zschiesche; Stefan Schramm; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3325Thu, 10 Nov 2005 10:29:25 +0100Particle ratios from AGS to RHIC in an interacting hadronic model
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3316
Abstract: The measured particle ratios in central heavy-ion collisions at RHIC-BNL are investigated within a chemical and thermal equilibrium chiral SU(3) Ã É approach. The commonly adopted non-interacting gas calculations yield temperatures close to or above the critical temperature for the chiral phase transition, but without taking into account any interactions. In contrast, the chiral SU(3) model predicts temperature and density dependent effective hadron masses and effective chemical potentials in the medium and a transition to a chirally restored phase at high temperatures or chemical potentials. Three different parametrizations of the model, which show different types of phase transition behaviour, are investigated. We show that if a chiral phase transition occured in those collisions, freezing of the relative hadron abundances in the symmetric phase is excluded by the data. Therefore, either very rapid chemical equilibration must occur in the broken phase, or the measured hadron ratios are the outcome of the dynamical symmetry breaking. Furthermore, the extracted chemical freeze-out parameters differ considerably from those obtained in simple non-interacting gas calculations. In particular, the three models yield up to 35 MeV lower temperatures than the free gas approximation. The inmedium masses turn out to differ up to 150 MeV from their vacuum values.Detlef Zschiesche; Gebhard Zeeb; Kerstin Paech; Horst Stöcker; Stefan Schrammarticlehttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3316Wed, 09 Nov 2005 11:21:07 +0100Kaons and antikaons in hot and dense hadronic matter
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3315
Abstract: The medium modification of kaon and antikaon masses, compatible with low energy KN scattering data, are studied in a chiral SU(3) model. The mutual interactions with baryons in hot hadronic matter and the e ects from the baryonic Dirac sea on the K( ¯K ) masses are examined. The in-medium masses from the chiral SU(3) e ective model are compared to those from chiral perturbation theory. Furthermore, the influence of these in-medium e ects on kaon rapidity distributions and transverse energy spectra as well as the K, ¯K flow pattern in heavy-ion collision experiments at 1.5 to 2 A·GeV are investigated within the HSD transport approach. Detailed predictions on the transverse momentum and rapidity dependence of directed flow v1 and the elliptic flow v2 are provided for Ni+Ni at 1.93 A·GeV within the various models, that can be used to determine the in-medium K± properties from the experimental side in the near future.Amruta Mishra; Elena L. Bratkovskaya; Jürgen Schaffner-Bielich; Stefan Schramm; Horst Stöckerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3315Wed, 09 Nov 2005 11:16:29 +0100Impact of baryon resonances on the chiral phase transition at finite temperature and density
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3345
We study the phase diagram of a generalized chiral SU(3)-flavor model in mean-field approxi- mation. In particular, the influence of the baryon resonances, and their couplings to the scalar and vector fields, on the characteristics of the chiral phase transition as a function of temperature and baryon-chemical potential is investigated. Present and future finite-density lattice calculations might constrain the couplings of the fields to the baryons. The results are compared to recent lattice QCD calculations and it is shown that it is non-trivial to obtain, simultaneously, stable cold nuclear matter.Detlef Zschiesche; Gebhard Zeeb; Stefan Schramm; Horst Stöckerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3345Wed, 09 Nov 2005 09:22:24 +0100