Year of publication
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- Subthreshold antiproton production in heavy ion collisions (1993)
- We present a RQMD calculation of antiproton yields and their momentum distribution in Ne + NaF collisions at 2 GeV/u. The antiprotons can be produced below threshold due to multi-step excitations for which meson-baryon interactions play a considerable role. In this system the annihilation probability for an initially produced antiproton is predicted to be about 65%.
- Hydrodynamic flow and jet induced mach shocks at RHIC and LHC (2007)
- We discuss the present collective flow signals for the phase transition to quark-gluon plasma (QGP) and the collective flow as a barometer for the equation of state (EoS). A study of Mach shocks induced by fast partonic jets propagating through the QGP is given. We predict a significant deformation of Mach shocks in central Au+Au collisions at RHIC and LHC energies as compared to the case of jet propagation in a static medium. Results of a hydrodynamical study of jet energy loss are presented.
- In-medium properties of D-mesons at FAIR (2006)
- We obtain the D-meson spectral density at finite temperature for the conditions of density and temperature expected at FAIR. We perform a self-consistent coupled-channel calculation taking, as a bare interaction, a separable potential model. The Lambda_c (2593) resonance is generated dynamically. We observe that the D-meson spectral density develops a sizeable width while the quasiparticle peak stays close to the free position. The consequences for the D-meson production at FAIR are discussed.
- Baryon number and electric charge fluctuations in Pb+Pb collisions at SPS energies (2006)
- Event-by-event fluctuations of the net baryon number and electric charge in nucleus-nucleus collisions are studied in Pb+Pb at SPS energies within the HSD transport model. We reveal an important role of the fluctuations in the number of target nucleon participants. They strongly influence all measured fluctuations even in the samples of events with rather rigid centrality trigger. This fact can be used to check different scenarios of nucleus-nucleus collisions by measuring the multiplicity fluctuations as a function of collision centrality in fixed kinematical regions of the projectile and target hemispheres. The HSD results for the event-by-event fluctuations of electric charge in central Pb+Pb collisions at 20, 30, 40, 80 and 158 A GeV are in a good agreement with the NA49 experimental data and considerably larger than expected in a quark-gluon plasma. This demonstrate that the distortions of the initial fluctuations by the hadronization phase and, in particular, by the final resonance decays dominate the observable fluctuations.
- Longitudinal fluid-dynamics for ultrarelativistic heavy-ion collisions (2006)
- We develop a 1+1 dimensional hydrodynamical model for central heavy-ion collisions at ultrarelativistic energies. Deviations from Bjorken's scaling are taken into account by implementing finite-size profiles for the initial energy density. The calculated rapidity distributions of pions, kaons and antiprotons in central Au+Au collisions at the c.m. energy 200 AGeV are compared with experimental data of the BRAHMS Collaboration. The sensitivity of the results to the choice of the equation of state, the parameters of initial state and the freeze-out conditions is investigated. The best fit of experimental data is obtained for a soft equation of state and Gaussian-like initial profiles of the energy density.
- Signatures for black hole production from hadronic observables at the Large Hadron Collider (2006)
- The concept of Large Extra Dimensions (LED) provides a way of solving the Hierarchy Problem which concerns the weakness of gravity compared with the strong and electro-weak forces. A consequence of LED is that miniature Black Holes (mini-BHs) may be produced at the Large Hadron Collider in p+p collisions. The present work uses the CHARYBDIS mini-BH generator code to simulate the hadronic signal which might be expected in a mid-rapidity particle tracking detector from the decay of these exotic objects if indeed they are produced. An estimate is also given for Pb+Pb collisions.
- Mini black holes in the first year of the LHC : discovery through di-jet suppression, mono-jet emission and ionising tracks in ALICE (2006)
- The experimental signatures of TeV-mass black hole (BH) formation in heavy ion collisions at the LHC is examined. We find that the black hole production results in a complete disappearance of all very high p_T (> 500 GeV) back-to-back correlated di-jets of total mass M > M_f ~ 1 TeV. We show that the subsequent Hawking-decay produces multiple hard mono-jets and discuss their detection. We study the possibility of cold black hole remnant (BHR) formation of mass ~ M_f and the experimental distinguishability of scenarios with BHRs and those with complete black hole decay. Due to the rather moderate luminosity in the first year of LHC running the least chance for the observation of BHs or BHRs at this early stage will be by ionizing tracks in the ALICE TPC. Finally we point out that stable BHRs would be interesting candidates for energy production by conversion of mass to Hawking radiation.
- DD correlations as a sensitive probe for thermalization in high-energy nuclear collisions (2006)
- We propose to measure azimuthal correlations of heavy-flavor hadrons to address the status of thermalization at the partonic stage of light quarks and gluons in high-energy nuclear collisions. In particular, we show that hadronic interactions at the late stage cannot significantly disturb the initial back-to-back azimuthal correlations of DDbar pairs. Thus, a decrease or the complete absence of these initial correlations does indicate frequent interactions of heavy-flavor quarks and also light partons in the partonic stage, which are essential for the early thermalization of light partons.
- Mini black holes at the LHC : discovery through di-jet suppression, mono-jet emission and a supersonic boom in the quark-gluon plasma in ALICE, ATLAS and CMS (2006)
- We examine experimental signatures of TeV-mass black hole formation in heavy ion collisions at the LHC. We find that the black hole production results in a complete disappearance of all very high p_T (> 500 GeV) back-to-back correlated di-jets of total mass M > M_f ~ 1 TeV. We show that the subsequent Hawking-decay produces multiple hard mono-jets and discuss their detection. We study the possibility of cold black hole remnant (BHR) formation of mass ~ M_f and the experimental distinguishability of scenarios with BHRs and those with complete black hole decay. Finally we point out that a Heckler-Kapusta-Hawking plasma may form from the emitted mono-jets. In this context we present new simulation data of Mach shocks and of the evolution of initial conditions until the freeze-out.
- Nuclear equation of state from the nonlinear relativistic mean field theory (1988)
- The properties of symmetric nuclear matter are investigated in the nonlinear relativistic mean field theory of nuclear matter. We consider the constraints imposed by four nuclear ground state properties on the coupling constants and on the equation of state at zero and at finite temperature. We find that the compression constant K(ρ0) as well as the temperature is irrelevant for the stiffness of the equation of state for m*(ρ0)≤0.7. The main point is that the relativistic mean field theory exhibits acausal and unphysical behavior for compressibilities below K(ρ0)=200 MeV. Every set of coupling constants with a negative quartic coupling constant c is unstable against small quantum fluctuations.