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Register a new userThe comparison of the 3-fluid dynamic model with experimental data
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Valeriy Kizka Alexandrovich
Publication date
2015
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and research's language is
English
Authors
V.A. Kizka
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The method of comparison of theoretical predictions with experimental data had been developed.This method allows estimate the quality of theory. Published theoretical data of the three-fluid dynamic (3FD) model applied to the experimental data from heavy-ion collisions at the energy range $sqrt{s_{NN}},=,2.7 - 63$ GeV were used as example of application of the developed methodology.
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Background. Neutrino-induced pion production can give important informationon the axial coupling to nucleon resonances. Furthermore, pion production represents a major background to quasielastic-like events. Single pion production data from the MiniBooNE in charged current neutrino scattering in mineral oil appeared higher than expected within conventional theoretical approaches. Purpose. We aim to investigate which model parameters affect the calculated cross section and how they do this. Method. The Giessen Boltzmann--Uehling--Uhlenbeck (GiBUU) model is used for an investigation of neutrino-nucleus reactions. Results. Presented are integrated and differential cross sections for 1pi^+ and 1pi^0 production before and after final state interactions in comparison with the MiniBooNE data. Conclusions. For the MiniBooNE flux all processes (QE, 1pi-background, Delta, higher resonance production, DIS) contribute to the observed final state with one pion of a given charge. The uncertainty in elementary pion production cross sections leads to a corresponding uncertainty in the nuclear cross sections. Final state interactions change the shape of the muon-related observables only slightly, but they significantly change the shape of pion distributions.
[Background] Experimental data from heavy-ion experiments at RHIC-BNL and LHC-CERN are quantitatively described using relativistic fluid dynamics. Even p+A and p+p collisions show signs of collective behavior describable in the same manner. Nevertheless, small system sizes and large gradients strain the limits of applicability of fluid-dynamical methods. [Purpose] The range of applicability of fluid dynamics for the description of the collective behavior, and in particular of the elliptic flow, of small systems needs to be explored. [Method] Results of relativistic fluid-dynamical simulations are compared with solutions of the Boltzmann equation in a longitudinally boost-invariant picture. As initial condition, several different transverse energy-density profiles for equilibrated matter are investigated. [Results] While there is overall a fair agreement of energy- and particle-density profiles, components of the shear-stress tensor are more sensitive to details of the implementation. The highest sensitivity is exhibited by quantities influenced by properties of the medium at freeze-out. [Conclusions] For some quantities, like the shear-stress tensor, agreement between fluid dynamics and transport theory extends into regions of Knudsen numbers and inverse Reynolds numbers where relativistic fluid dynamics is believed to fail.
A hybrid (hydrodynamics + hadronic transport) theoretical framework is assembled to model the bulk dynamics of relativistic heavy-ion collisions at energies accessible in the Beam Energy Scan (BES) program at the Relativistic Heavy-Ion Collider (RHIC) and the NA61/SHINE experiment at CERN. The systems energy-momentum tensor and net baryon current are evolved according to relativistic hydrodynamics with finite shear viscosity and non-zero net baryon diffusion. Our hydrodynamic description is matched to a hadronic transport model in the dilute region. With this fully integrated theoretical framework, we present a pilot study of the hadronic chemistry, particle spectra, and anisotropic flow. Phenomenological effects of a non-zero net-baryon current and its diffusion on hadronic observables are presented for the first time. The importance of the hadronic transport phase is also investigated.
We compare a relativistic covariant model for proton-proton bremsstrahlung with high-quality data from KVI. The agreement in large parts of phase space is satisfactory. However, remarkably large discrepancies are observed for specific kinematic regions. These failures are shown to occur primarily when the final two-nucleon system has energies less than about 15 MeV.
We demonstrate that the explanation of the neutron anomaly around $Wsim 1685$MeV in $gamma Nto eta N$ reactions provided by the $eta$MAID2018 isobar model is based on large violation of the flavour SU(3) symmetry in hadron interactions. This is yet another example of how conventional explanation (without invoking exotic narrow nucleon resonance) of the neutron anomaly metamorphoses into unconventional physics picture of hadron interactions. A possibility to mend the flavour SU(3) symmetry for some of resonances in $eta$MAID model is discussed.
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