Refine
Year of publication
Document Type
- Preprint (224)
- Article (152)
- Conference Proceeding (7)
- Report (2)
- Doctoral Thesis (1)
- Working Paper (1)
Has Fulltext
- yes (387)
Is part of the Bibliography
- no (387)
Keywords
- Kollisionen schwerer Ionen (47)
- heavy ion collisions (41)
- Quark-Gluon-Plasma (17)
- equation of state (14)
- QGP (13)
- quark-gluon plasma (12)
- Hadron (11)
- heavy-ion collisions (11)
- Quark Gluon Plasma (10)
- Zustandsgleichung (10)
- heavy ion collision (9)
- quark (9)
- collision (8)
- LHC (7)
- Meson (7)
- Quanten-Chromodynamik (7)
- Quark (7)
- UrQMD (7)
- meson (7)
- quark gluon plasma (7)
- quark matter (7)
- quark-gluon-plasma (7)
- Energie (6)
- Kollision (6)
- MEMOs (6)
- QCD (6)
- hadronic (6)
- relativistic (6)
- QMD (5)
- Quantum Chromodynamic (5)
- RHIC (5)
- Relativistic heavy-ion collisions (5)
- SPS (5)
- baryon (5)
- energy (5)
- hadron (5)
- nuclear reactions (5)
- nucleon (5)
- Bremsstrahlung (4)
- Dirac (4)
- Drell-Yan (4)
- QCD equation of state (4)
- Quark Materie (4)
- RQMD (4)
- bremsstrahlung (4)
- gluon (4)
- hadronic matter (4)
- heavy ion colliders (4)
- hydrodynamisches Modell (4)
- nuclear collisions (4)
- relativistic quantum molecular dynamics (4)
- schwere Ion Kollision (4)
- EOS (3)
- Heavy ion collisions (3)
- Kollisionen des schweren Ions (3)
- Materie (3)
- Meson production (3)
- Molekulare Dynamik (3)
- Neutronenstern (3)
- Nukleon (3)
- Strahl (3)
- Strangelets (3)
- Teilchen (3)
- Ultrarelativistic Quantum Molecular Dynamics (3)
- Zustandsgleichungen (3)
- black holes (3)
- hydrodynamical model (3)
- jet (3)
- kaon (3)
- neutralino (3)
- neutron star (3)
- nuclei (3)
- relativistisch (3)
- schwere Ion-Kollision (3)
- strangelets (3)
- Black holes (2)
- CDM (2)
- D-meson spectral density (2)
- Dichte (2)
- Dilepton (2)
- Dirac-Brueckner theory (2)
- Dirac-Brückner Theorie (2)
- Equation of state (2)
- Gluon (2)
- High Energy Physics - Phenomenology (2)
- Kaon (2)
- Kerne (2)
- Kernkollisionen (2)
- Lagrangian (2)
- Nambu Jona-Lasinio Modell (2)
- Nambu Jona-Lasinio model (2)
- Nuclear Theory (2)
- Nucleon (2)
- Partikelspektren (2)
- Phasenübergang (2)
- Pion (2)
- Plasma (2)
- QCD phase transition (2)
- Quanten Chromodynamik (2)
- Quantenchromodynamik (2)
- Quantum Chromodynamics (2)
- Quantum Molecular Dynamics (2)
- Quark gluon Plasma (2)
- Quark-Gluon Plasma (2)
- Statistical model (2)
- Temperatur (2)
- Tevatron (2)
- UrQMD Modell (2)
- Walecka model (2)
- antibaryon (2)
- antikaon (2)
- binary neutron star merger (2)
- bound state (2)
- cold dark matter (2)
- deep learning (2)
- degrees of freedom (2)
- dense matter (2)
- dichte Materie (2)
- dilepton (2)
- freeze out (2)
- gravitational wave (2)
- große Extradimensionen (2)
- hadronische Materie (2)
- hyperon (2)
- kalte dunkle Materie (2)
- kinetic equation (2)
- kinetische Gleichung (2)
- large extra dimensions (2)
- masse (2)
- matter (2)
- nuclear broadening effect (2)
- nuclear matter (2)
- nucleus-nucleus collisions (2)
- open and hidden charm (2)
- particle ratios (2)
- particle spectra (2)
- particles (2)
- pion (2)
- plasma (2)
- prompt photon (2)
- relativistic heavy ion collision (2)
- relativistische (2)
- relativistische schwere Ion Kollision (2)
- schwarze Löcher (2)
- schwere Ion-Kollisionen (2)
- schwere Ione (2)
- statistical coalescence model (2)
- statistisches Fusionsmodell (2)
- strange hadronic matter (2)
- supersymmetric particle (2)
- temperature (2)
- thermalization (2)
- ultrarelativistisch (2)
- ultrarelativistische (2)
- viscosity (2)
- (QGP) (1)
- 20Ne + 238U (1)
- AGS (1)
- Abhängigkeit von der Dichte (1)
- Absorption (1)
- Anisotropic flow (1)
- Anti-Kaon (1)
- Antikaon (1)
- Antinukleonen (1)
- Antiteilchen (1)
- Ar + Pb (800 MeV/nucleon) relativistic heavy-ion reactions (1)
- Ar+Ca (1)
- Ausfrieren (1)
- BEVALAC (1)
- Baryon (1)
- Baryon Resonance (1)
- Baryon-Resonanz (1)
- Bjorken Modell (1)
- Bjorken model (1)
- Boltzmann-Uehling-Uhlenbeck (1)
- Boltzmann-Uehling-Uhlenbeck Gleichung (1)
- Boltzmann-Uehling-Uhlenbeck equation (1)
- Bose (1)
- Bose-simulated pion production (1)
- CBM detector (1)
- CLVisc (1)
- Canonical suppression (1)
- Charm Produktion (1)
- Charmed mesons (1)
- Charmed quarks (1)
- Charmonium (1)
- Charmonium Produktion (1)
- Charmonium production (1)
- Chemical equilibration (1)
- Chemikalie (1)
- Chemische Gleichgewichtherstellung (1)
- Chiral effective model (1)
- Chiral symmetries (1)
- Cluster distribution (1)
- Cluster integrals (1)
- Collective flow (1)
- Collision (1)
- Conservation Laws (1)
- Conserved charge fluctuations (1)
- Convolutional (1)
- Coupled-channel self-consistent calculation (1)
- D-Dbar (1)
- DN interaction (1)
- Deep learning (1)
- Deuteron (1)
- Dielectron (1)
- Dielektron (1)
- Distributed software development (1)
- Drell-Yan production (1)
- Drell-Yan ratio (1)
- Drell-Yan-Prozess (1)
- Dynamic transport (1)
- Dynamik (1)
- Dyson-Schwinger equation (1)
- E1ab=400 MeV/nucleon fluid dynamics (1)
- Earthquake waveforms (1)
- Elab=393 MeV/nucleon (1)
- Elektron (1)
- Elementarteilchen (1)
- Elementary particle (1)
- Equation of State (1)
- Ereignisschwankungen (1)
- Erhaltungsgesetz (1)
- European electricity grid (1)
- Event-by-event fluctuations (1)
- Excluded volume (1)
- Extra dimensions (1)
- FAIR (1)
- Finite temperature (1)
- First-motion polarity (1)
- Fluid dynamics (1)
- Freeze Out (1)
- Freeze out (1)
- Freiheitsgrad (1)
- Freiheitsgrade (1)
- GSI (1)
- Geometrical modelling (1)
- Geometrisches Modellieren (1)
- Gleichgewicht (1)
- Gluon-Plasma (1)
- Gyromagnetic Moment (1)
- HBT correlation (1)
- HBT interferometry (1)
- HBT puzzle (1)
- HICs (1)
- Hadron Gas Modell (1)
- Hadron Materie (1)
- Hadron potentials (1)
- Hadron resonance gas (1)
- Hadronenbeschleuniger (1)
- Hartree (1)
- Heavy Ion Phenomenology (1)
- Heavy-ion physics (1)
- High Energy Heavy Ion Collisions (1)
- Hohe Energie (1)
- Homogeneous nucleation (1)
- Hybrid model (1)
- Hypermaterie (1)
- IQMD Modell (1)
- IQMD model (1)
- Imaginary chemical potential (1)
- In-Medium Zerfall (1)
- Information theory and computation (1)
- J/psi Erhöhung (1)
- J/psi Unterdrückung (1)
- J/psi enhancement (1)
- J/psi mesons (1)
- J/psi suppression (1)
- J/psi yield (1)
- J/ϕ (1)
- K-Meson (1)
- Kaons (1)
- Kern-Kern Kollision (1)
- Kern-Kern Kollisionen (1)
- Kernkollision (1)
- Kernmaterie (1)
- Kernreaktion Modell und Methoden (1)
- Kollisionen schwere Ionen (1)
- Korrelation (1)
- Kosmischer Strahl (1)
- Lagrangian . equation of state (1)
- Lambda-c(2593) resonance (1)
- Large Hadron Collider (1)
- Lepton (1)
- Light nuclei production (1)
- Local thermodynamical equilibrium (1)
- Lorentz (1)
- Lorentz contraction (1)
- Mach Shocks (1)
- Masse (1)
- Massenspektrum (1)
- Metastable Exotic Multistrange Objects (1)
- Modell (1)
- Monte Carlo Modell (1)
- Monte Carlo model (1)
- Monte-Carlo model for relativistic heavy ion collisions (1)
- Nambu Jona Lasinio Modell (1)
- Nambu Jona Lasinio model (1)
- Nambu-Jona-Lasinio (1)
- Nambu-Jona-Lasinio Modell (1)
- Nambu-Jona-Lasinio model (1)
- Ne+U (1)
- Neutron (1)
- Neutronensterne (1)
- Nichtgleichgewicht (1)
- Nichtumkehrbarkeit (1)
- Non-equilibrium effects (1)
- Nuclear Experiment (1)
- Nuclear interactions (1)
- Nuclear-reaction models and methods (1)
- OMD (1)
- Objectoriented technology (1)
- Objektorientierte Technologie (1)
- Particle Spectra (1)
- Particle and resonance production (1)
- Particle interactions (1)
- Partikel (1)
- Partikel-Wechselwirkungen (1)
- Partikelzahlschwankung (1)
- Pb+Pb collisions (1)
- Photon (1)
- Pion Gas (1)
- Pion-Produktion (1)
- PointNet (1)
- Potential (1)
- Produktion von pentaquark (1)
- Proton number fluctuations (1)
- Protonen (1)
- QCD Phenomenology (1)
- QCD medium (1)
- QCD phase diagram (1)
- QCD plasma (1)
- QGP hadrons phase transition (1)
- QGP signals (1)
- QMC (1)
- QMD Modell (1)
- QMD model (1)
- QSM (1)
- Quanten Chromodynamic (1)
- Quanten-Molekular-Dynamic (1)
- Quanten-Molekular-Dynamik (1)
- Quanten-Molekulardynamik (1)
- Quantendynamik (1)
- Quantenmolekulardynamik (1)
- Quantum (1)
- Quantum chromodynamics (1)
- Quark Antiquark (1)
- Quark gluon plasma (1)
- Quark-Sterne (1)
- Quarkmaterie (1)
- Quarkonium (1)
- RHIC energies (1)
- Raum Zeit (1)
- Relativistic Excluded Volumes (1)
- Relativistic Heavy Ion Collider (1)
- Relativistisch (1)
- Relativistische Kollisionen des schwere Ions (1)
- Rho-Meson (1)
- SENECA model (1)
- SHM (1)
- SU (3) - Modell (1)
- SU (3) - Symmetrie (1)
- SU (3) Modell (1)
- SU(3) model (1)
- SU(3)-model (1)
- SU(3)-symmetry (1)
- Schwankung (1)
- Schwerionenphysik (1)
- Simulation (1)
- Skalarpotential (1)
- Software engineering (1)
- Softwaretechnik (1)
- Spektren (1)
- Stoßwelle (1)
- Super Proton Synchrotron (1)
- Susceptibilities (1)
- Symmetrie (1)
- Teilchenbeschleuniger (1)
- Teilchenspektren (1)
- Teilchenverteilung (1)
- Theoretical nuclear physics (1)
- Transport (1)
- Transportmodell (1)
- Two-component and Multi-component Hadron Gas (1)
- URQMD (1)
- Ultra-relativistic Quantum Molecular Dynamic (1)
- Ultra-relativistic Quantum Molecular Dynamics model (1)
- Ultrarelativisitic Quantum Molecular Dynamics model (1)
- Ultrarelativisitisches (1)
- Ultrarelativistic Quantum Molecular Model (1)
- Ultrarelativistisches Quant Molekular Dynamik (1)
- Ultrarelativistisches Quant Molekulares Modell (1)
- UrQMD model (1)
- Van der Waals (1)
- Van der Waals Excluded Volume Model (1)
- Van der Waals model (1)
- Vektorpotential (1)
- Verbreitung (1)
- Vielkörperkorrelationen (1)
- Walecka Modell (1)
- Walecka-Modell (1)
- Walecka-model (1)
- Wellen (Physik) / shock waves in nuclear matter (1)
- Zeitabhängig (1)
- Zusammenstoß (1)
- absorption (1)
- angular distribution (1)
- anti-kaon (1)
- anti-nucleons (1)
- antiparticles (1)
- begrenzte Kerne (1)
- bestimmte Zustände (1)
- binary neutron star mergers (1)
- black hole (1)
- bound states (1)
- broadening (1)
- central collisions (1)
- centrality (1)
- charm (1)
- charm and bottom Produktion (1)
- charm and bottom production (1)
- chemical (1)
- chemical freezeout (1)
- chemisches Ausfrieren (1)
- chiral (1)
- chiral SU (3) (1)
- chiral SU(3) (1)
- chiral SU(3) model (1)
- chiral phase (1)
- cluster expansion model (1)
- cold baryon rich matter (1)
- cold quark matter (1)
- collective flow (1)
- color current (1)
- coloured quark dynamic (1)
- compressible flow (1)
- compression (1)
- conservation law (1)
- conservation laws (1)
- coupled-channel self-consistent calculation (1)
- cross sections (1)
- dark matter (1)
- dense (1)
- density and momentum dependence (1)
- density isomers (1)
- density perturbations (1)
- deuteron (1)
- dileptons (1)
- directed flow (1)
- double differential cross sections (1)
- dunkle Materie (1)
- eigenartige Signale (1)
- electron (1)
- elliptic flow analysis (1)
- energie (1)
- equilibrium (1)
- excited nuclei (1)
- exotic matter (1)
- exotische Materie (1)
- femtoscopy data (1)
- finite baryon density (1)
- finite nuclei (1)
- finite temperature (1)
- flow (1)
- flow allocation (1)
- flow of nucleons (1)
- fluid dynamics (1)
- fluid dynamics with thermal breakup (1)
- freezeout (1)
- gluon plasma (1)
- gravitational waves (1)
- großer hadron collider (1)
- gyromagnetic moment (1)
- hadron hadron Kollision (1)
- hadron hadron collision (1)
- hadron interaction models (1)
- hadron matter (1)
- hadron yield (1)
- hadron-quark phase transition (1)
- hadronic fluctuation (1)
- hadronic freeze-out (1)
- hadronic model (1)
- hard-core (1)
- heat conduction (1)
- heavy Hagedorn states (1)
- heavy ion (1)
- heavy ions (1)
- heavy-flavor quarks (1)
- heavy-ion reaction (1)
- heiße Kernmaterie (1)
- heiße Materie (1)
- heiße Pion Materie (1)
- heiße hadronic Materie (1)
- heiße und dichte Kernmaterie (1)
- heiße und dichte Materie (1)
- hidden charm production (1)
- high energie (1)
- high energy (1)
- high energy cosmic ray (1)
- high energy physics (1)
- high-energy nuclear collisions (1)
- hitze (1)
- hohe Energie (1)
- homogene Nukleation (1)
- hot (1)
- hot and dense matter (1)
- hot and dense nuclear matter (1)
- hot hadronic matter (1)
- hot hypernuclear matter (1)
- hot matter (1)
- hot pion matter (1)
- hybrid approach to air shower simulations (1)
- hydrodynami (1)
- hydrodynamic description (1)
- hydrodynamic model (1)
- hydrodynamics (1)
- hypermatter (1)
- hyperonic Materie (1)
- hyperonic matter (1)
- ideal gas (1)
- ideales Gas (1)
- impact parameter (1)
- in-medium decay (1)
- in-medium properties (1)
- interaction (1)
- irreversibility state (1)
- kaons (1)
- kinetic energy (1)
- kinetisches Ausfrieren (1)
- kinetisches Modell (1)
- kollektive strom (1)
- kollidieren (1)
- lange hadron collider (1)
- large hadron collider (1)
- lepton (1)
- light nuclei production (1)
- lokales thermodynamisches Gleichgewicht (1)
- low energy hadronic model (1)
- machine learning (1)
- many-body correlations (1)
- mass spectra (1)
- meson mass (1)
- microscopic model (1)
- microscopic transport theory (1)
- mikroskopische Transporttheorie (1)
- mikroskopisches Modell (1)
- minimal length (1)
- minimale Länge (1)
- mixing of hadron sources (1)
- muon (1)
- neutron and proton chemical potential (1)
- neutron star properties (1)
- neutron stars (1)
- neutron-star-merger (1)
- niobium (1)
- non-equilibrium dynamics (1)
- non-equilibrium quantum field dynamics (1)
- nuclear (1)
- nuclear fluid dynamics (1)
- nuclear hydrodynamics (1)
- nuclear shadowing (1)
- nuclear system (1)
- nucleon and nuclear cross sections (1)
- nuclera reactions (1)
- offene charm Produktion (1)
- open and hidden charm production (1)
- open charm production (1)
- open charm yield (1)
- pQCD (1)
- parity-doublet model (1)
- particle collisions (1)
- particle distribution (1)
- particle number fluctuations (1)
- partonic (1)
- perturbative Quantum Chromodynamic (1)
- phase transition (1)
- photon (1)
- pion condensation (1)
- pion gas (1)
- pions (1)
- power system analysis; (1)
- production of pentaquark (1)
- quant molekular dynamic (1)
- quantum chromodynamic (1)
- quantum molecular dynamic (1)
- quantum molecular dynamics model (1)
- quantum statistical model (1)
- quark antiquark (1)
- quark gluon Plasma (1)
- quark shadowing (1)
- quark-meson coupling model (1)
- quarkonium (1)
- quasi-stable black holes (1)
- quasistabile schwarze Löcher (1)
- reich (1)
- relativistic fluid of quarks (1)
- relativistic heavy ion collider (1)
- relativistic heavy-ion reactions (1)
- relativistic transport model (1)
- relativistischer Schwerionen-Zusammenstoßer (1)
- resonance (1)
- rho meson (1)
- rich (1)
- scalar potential (1)
- schwarzes Loch (1)
- schwere Hagedorn Zustände (1)
- schwere Ionen Kollision (1)
- schweres Ion (1)
- second cluster integral (1)
- shock waves (1)
- space-momentum correlation (1)
- space-time (1)
- spectra (1)
- stabile kalte Kerne (1)
- stable cold nuclear matter (1)
- statistical model (1)
- statistisches Modell (1)
- strange (1)
- strange quark star (1)
- strangeness (1)
- strangeness signals (1)
- superheavy (1)
- superheavy nuclei (1)
- superschwer (1)
- superschwere Kerne (1)
- supersymmetrische Partikel (1)
- symmetry potential (1)
- system (1)
- thermal (1)
- time dependent (1)
- transmission cost allocation (1)
- transport models (1)
- two-proton correlations (1)
- ultra-relativistic heavy ion collision (1)
- ultrarelativistic (1)
- ultrarelativistic energie (1)
- ultrarelativistic heavy ion collision (1)
- ultrarelativistic heavy-ion collision (1)
- ultrarelativistische Kollision des schweren Ionen (1)
- ultrarelativistische energie (1)
- ultrarelativistische schwere Ion Kollision (1)
- van der Waals (1)
- vector mesons (1)
- vector potential (1)
- zweite Gruppenintegral (1)
Institute
In the framework of the relativistic quantum dynamics approach we investigate antiproton observables in Au-Au collisions at 10.7A GeV. The rapidity dependence of the in-plane directed transverse momentum p(y) of p's shows the opposite sigh of the nucleon flow, which has indeed recently been discovered at 10.7A GeV by the E877 group. The "antiflow" of p's is also predicted at 2A GeV and at 160 A GeV and appears at all energies also for pi's and K's. These predicted p anticorrelations are a direct proof of strong p annihilation in massive heavy ion reactions.
We study the time scale for pressure equilibration in heavy ion collisions at AGS energies within the three-fluid hydrodynamical model and a microscopic cascade model (UrQMD). We find that kinetic equilibrium is reached in both models after a time of 5 fm/c (center-of-mass time). Thus, observables which are sensitive to the early stage of the reaction differ considerably from the expectations within the instant thermalization scenario (one-fluid hydrodynamical model).
Abstract: We study transverse expansion and directed flow in Au(11AGeV)Au reactions within a multi-fluid dynamical model. Although we do not employ an equation of state (EoS) with a first order phase transition, we find a slow increase of the transverse velocities of the nucleons with time. A similar behaviour can be observed for the directed nucleon flow. This is due to non-equilibrium e ects which also lead to less and slower conversion of longitudinal into transverse momentum. We also show that the proton rapidity distribution at CERN energies, as calculated within this model, agrees well with the preliminary NA44-data.
A new method of event characterization based on Deep Learning is presented. The PointNet models can be used for fast, online event-by-event impact parameter determination at the CBM experiment. For this study, UrQMD and the CBM detector simulation are used to generate Au+Au collision events at 10 AGeV which are then used to train and evaluate PointNet based architectures. The models can be trained on features like the hit position of particles in the CBM detector planes, tracks reconstructed from the hits or combinations thereof. The Deep Learning models reconstruct impact parameters from 2-14 fm with a mean error varying from -0.33 to 0.22 fm. For impact parameters in the range of 5-14 fm, a model which uses the combination of hit and track information of particles has a relative precision of 4-9% and a mean error of -0.33 to 0.13 fm. In the same range of impact parameters, a model with only track information has a relative precision of 4-10% and a mean error of -0.18 to 0.22 fm. This new method of event-classification is shown to be more accurate and less model dependent than conventional methods and can utilize the performance boost of modern GPU processor units.
The SENECA model, a new hybrid approach to air shower simulations, is presented. It combines the use of efficient cascade equations in the energy range where a shower can be treated as one-dimensional, with a traditional Monte Carlo method which traces individual particles. This allows one to reproduce natural fluctuations of individual showers as well as the lateral spread of low energy particles. The model is quite efficient in computation time. As an application of the new approach, the influence of the low energy hadronic models on shower properties for AUGER energies is studied. We conclude that these models have a significant impact on the tails of lateral distribution functions, and deserve therefore more attention.
The coordinate and momentum space configurations of the net baryon number in heavy ion collisions that undergo spinodal decomposition, due to a first-order phase transition, are investigated using state-of-the-art machine-learning methods. Coordinate space clumping, which appears in the spinodal decomposition, leaves strong characteristic imprints on the spatial net density distribution in nearly every event which can be detected by modern machine learning techniques. On the other hand, the corresponding features in the momentum distributions cannot clearly be detected, by the same machine learning methods, in individual events. Only a small subset of events can be systematically differ- entiated if only the momentum space information is available. This is due to the strong similarity of the two event classes, with and without spinodal decomposition. In such sce- narios, conventional event-averaged observables like the baryon number cumulants signal a spinodal non-equilibrium phase transition. Indeed the third-order cumulant, the skewness, does exhibit a peak at the beam energy (Elab = 3–4 A GeV), where the transient hot and dense system created in the heavy ion collision reaches the first-order phase transition.
A micro-canonical treatment is used to study particle production in pp collisions. First this micro-canonical treatment is compared to some canonical ones. Then proton, antiproton and pion 4 pi multiplicities from proton-proton collisions at various center of mass energies are used to fix the micro-canonical parameters (E) and (V). The dependences of the micro-canonical parameters on the collision energy are parameterised for the further study of pp reactions with this micro-canonical treatment.
A study of secondary Drell-Yan production in nuclear collisions is presented for SPS energies. In addition to the lepton pairs produced in the initial collisions of the projectile and target nucleons, we consider the potentially high dilepton yield from hard valence antiquarks in produced mesons and antibaryons. We calculate the secondary Drell-Yan contributions taking the collision spectrum of hadrons from the microscopic model URQMD. The con- tributions from meson-baryon interactions, small in hadron-nucleus interac- tions, are found to be substantial in nucleus-nucleus collisions at low dilepton masses. Preresonance collisions of partons may further increase the yields.
We predict the formation of highly dense baryon-rich resonance matter in Au+Au collisions at AGS energies. The final pion yields show observable signs for resonance matter. The Delta1232 resonance is predicted to be the dominant source for pions of small transverse momenta. Rescattering e ects consecutive excitation and deexcitation of Delta's lead to a long apparent life- time (> 10 fm/c) and rather large volumina (several 100 fm3) of the Delta-matter state. Heavier baryon resonances prove to be crucial for reaction dynamics and particle production at AGS.
The thermal fit to preliminary HADES data of Au+Au collisions at sNN=2.4 GeV shows two degenerate solutions at T≈50 MeV and T≈70 MeV. The analysis of the same particle yields in a transport simulation of the UrQMD model yields the same features, i.e. two distinct temperatures for the chemical freeze-out. While both solutions yield the same number of hadrons after resonance decays, the feeddown contribution is very different for both cases. This highlights that two systems with different chemical composition can yield the same multiplicities after resonance decays. The nature of these two minima is further investigated by studying the time-dependent particle yields and extracted thermodynamic properties of the UrQMD model. It is confirmed, that the evolution of the high temperature solution resembles cooling and expansion of a hot and dense fireball. The low temperature solution displays an unphysical evolution: heating and compression of matter with a decrease of entropy. These results imply that the thermal model analysis of systems produced in low energy nuclear collisions is ambiguous but can be interpreted by taking also the time evolution and resonance contributions into account.
A novel method for identifying the nature of QCD transitions in heavy-ion collision experiments is introduced. PointNet based Deep Learning (DL) models are developed to classify the equation of state (EoS) that drives the hydrodynamic evolution of the system created in Au-Au collisions at 10 AGeV. The DL models were trained and evaluated in different hypothetical experimental situations. A decreased performance is observed when more realistic experimental effects (acceptance cuts and decreased resolutions) are taken into account. It is shown that the performance can be improved by combining multiple events to make predictions. The PointNet based models trained on the reconstructed tracks of charged particles from the CBM detector simulation discriminate a crossover transition from a first order phase transition with an accuracy of up to 99.8%. The models were subjected to several tests to evaluate the dependence of its performance on the centrality of the collisions and physical parameters of fluid dynamic simulations. The models are shown to work in a broad range of centralities (b=0–7 fm). However, the performance is found to improve for central collisions (b=0–3 fm). There is a drop in the performance when the model parameters lead to reduced duration of the fluid dynamic evolution or when less fraction of the medium undergoes the transition. These effects are due to the limitations of the underlying physics and the DL models are shown to be superior in its discrimination performance in comparison to conventional mean observables.
A primordial state of matter consisting of free quarks and gluons that existed in the early universe a few microseconds after the Big Bang is also expected to form in high-energy heavy-ion collisions. Determining the equation of state (EoS) of such a primordial matter is the ultimate goal of high-energy heavy-ion experiments. Here we use supervised learning with a deep convolutional neural network to identify the EoS employed in the relativistic hydrodynamic simulations of heavy ion collisions. High-level correlations of particle spectra in transverse momentum and azimuthal angle learned by the network act as an effective EoS-meter in deciphering the nature of the phase transition in quantum chromodynamics. Such EoS-meter is model-independent and insensitive to other simulation inputs including the initial conditions for hydrodynamic simulations.
Relying on the existing estimates for the production cross sections of mini black holes in models with large extra dimensions, we review strategies for identifying those objects at collider experiments. We further consider a possible stable final state of such black holes and discuss their characteristic signatures. Keywords: Black holes
We introduce a transport approach which combines partonic and hadronic degrees of freedom on an equal footing and discuss the resulting reaction dynamics. The initial parton dynamics is modeled in the framework of the parton cascade model, hadronization is performed via a cluster hadronization model and configuration space coalescence, and the hadronic phase is described by a microscopic hadronic transport approach. The resulting reaction dynamics indicates a strong influence of hadronic rescattering on the space-time pattern of hadronic freeze-out and on the shape of transverse mass spectra. Freeze-out times and transverse radii increase by factors of 2 3 depending on the hadron species.
The transverse momentum dependence of the anisotropic flow v_2 for pi, K, nucleon, Lambda, Xi and Omega is studied for Au+Au collisions at sqrt s_NN = 200 GeV within two independent string-hadron transport approaches (RQMD and UrQMD). Although both models reach only 60% of the absolute magnitude of the measured v_2, they both predict the particle type dependence of v_2, as observed by the RHIC experiments: v_2 exhibits a hadron-mass hierarchy (HMH) in the low p_T region and a number-of-constituent-quark (NCQ) dependence in the intermediate p_T region. The failure of the hadronic models to reproduce the absolute magnitude of the observed v_2 indicates that transport calculations of heavy ion collisions at RHIC must incorporate interactions among quarks and gluons in the early, hot and dense phase. The presence of an NCQ scaling in the string-hadron model results suggests that the particle-type dependencies observed in heavy-ion collisions at intermediate p_T are related to the hadronic cross sections in vacuum rather than to the hadronization process itself, as suggested by quark recombination models.
A sign reversal of the directed flow parameter v1 in the central rapidity region in Au+Au collisions at s = 200 AGeV is predicted. This anti-flow is shown to be linked to the expansion of the hot matter created. In line with this observation the predicted elliptic flow parameter v2 of various particle species is linked to the mean free path of these particles.
We present a calculation of antiproton yields in Si+Al and Si+Au collisions at 14.5A GeV in the framework of the relativistic quantum molecular dynamics approach (RQMD). Multistep processes lead to the formation of high-mass flux tubes. Their decay dominates the initial antibaryon yield. However, the subsequent annihilation in the surrounding baryon-rich matter suppresses the antiproton yield considerably: Two-thirds of all antibaryons are annihilated even for the light Si+Al system. Comparisons with preliminary data of the E802 experiment support this analysis.
Antibaryons bound in nuclei
(2004)
We study the possibility of producing a new kind of nuclear systems which in addition to ordinary nucleons contain a few antibaryons (B = p, , etc.). The properties of such systems are described within the relativistic mean field model by employing G parity transformed interactions for antibaryons. Calculations are first done for infinite systems and then for finite nuclei from 4He to 208Pb. It is demonstrated that the presence of a real antibaryon leads to a strong rearrangement of a target nucleus resulting in a significant increase of its binding energy and local compression. Noticeable e ects remain even after the antibaryon coupling constants are reduced by factor 3 4 compared to G parity motivated values. We have performed detailed calculations of the antibaryon annihilation rates in the nuclear environment by applying a kinetic approach. It is shown that due to significant reduction of the reaction Q values, the in medium annihilation rates should be strongly suppressed leading to relatively long lived antibaryon nucleus systems. Multi nucleon annihilation channels are analyzed too. We have also estimated formation probabilities of bound B + A systems in pA reactions and have found that their observation will be feasible at the future GSI antiproton facility. Several observable signatures are proposed. The possibility of producing multi quark antiquark clusters is discussed. PACS numbers: 25.43.+t, 21.10.-k, 21.30.Fe, 21.80.+a
In the framework of RQMD we investigate antiproton observables in massive heavy ion collisions at AGS energies and compare to preliminary results of the E878 collaboration. We focus here on the considerable influence of the real part of an antinucleon nucleus optical potential on the ¯p momentum spectra. Pacs-numbers: 14.20 Dh, 25.70.-z