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  • 1
    In: International Journal of Modern Physics E, World Scientific Pub Co Pte Ltd, Vol. 29, No. 11 ( 2020-11), p. 2040009-
    Kurzfassung: From the analysis of light (anti)nuclei multiplicities that were measured recently by the ALICE collaboration in Pb+Pb collisions at the center-of-mass collision energy [Formula: see text][Formula: see text] TeV, there arose a highly nontrivial question about the excluded volume of composite particles. Surprisingly, the hadron resonance gas model (HRGM) is able to perfectly describe the light (anti) nuclei multiplicities under various assumptions. Thus, one can consider the (anti)nuclei with a vanishing hard-core radius (as the point-like particles) or with the hard-core radius of proton, but the fit quality is the same for these assumptions. It is clear, however, that such assumptions are unphysical. Hence we obtain a formula for the classical excluded volume of loosely bound light nuclei consisting of A baryons. To implement a new formula into the HRGM, we have to modify the induced surface tension concept to treat the hadrons and (anti)nuclei on the same footing. We perform a thorough analysis of hadronic and (anti)nuclei multiplicities measured by the ALICE collaboration. The HRGM with the induced surface tension allows us to verify different assumptions on the values of hard-core radii and different scenarios of chemical freeze-out of (anti)nuclei. It is shown that the unprecedentedly high quality of fit [Formula: see text] is achieved, if the chemical freeze-out temperature of hadrons is about [Formula: see text] [Formula: see text]MeV, while the one for all (anti)nuclei is [Formula: see text] [Formula: see text]MeV.
    Materialart: Online-Ressource
    ISSN: 0218-3013 , 1793-6608
    Sprache: Englisch
    Verlag: World Scientific Pub Co Pte Ltd
    Publikationsdatum: 2020
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
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    World Scientific Pub Co Pte Ltd ; 2007
    In:  International Journal of Modern Physics E Vol. 16, No. 07n08 ( 2007-08), p. 2301-2306
    In: International Journal of Modern Physics E, World Scientific Pub Co Pte Ltd, Vol. 16, No. 07n08 ( 2007-08), p. 2301-2306
    Kurzfassung: Energy dependence of nuclear shadowing and nuclear absorption is discussed in the framework of the Glauber–Gribov model and the AGK cutting rules. We calculate gluon shadowing using recent data on diffractive structure functions from HERA. Phenomenological implications for light particle production at SPS and RHIC are described and compared to charged particle production at mid- and forward rapidities. Comparison of the suppression at these energies leaves nevertheless little room for additional suppression phenomena.
    Materialart: Online-Ressource
    ISSN: 0218-3013 , 1793-6608
    Sprache: Englisch
    Verlag: World Scientific Pub Co Pte Ltd
    Publikationsdatum: 2007
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    In: International Journal of Modern Physics A, World Scientific Pub Co Pte Ltd, Vol. 36, No. 25 ( 2021-09-10)
    Kurzfassung: We present new results on the thermal production yield of a hypothetical state made of six quarks [Formula: see text] assuming its production in heavy-ion collisions at the CERN Large Hadron Collider (LHC). A state with this quark content and mass low enough to be stable against decay in timescales of the order of the age of the Universe has been hypothesized by one of us (G. Farrar) and has been discussed as a possible dark matter candidate. In this work, we address for the first time the thermal production rate that can be expected for this state in heavy-ion collisions at colliders. For this estimate we use a thermal model which has been shown to describe accurately the production of hadrons and nuclei in heavy-ion collisions at LHC energy. This estimate is of great relevance for sexaquark searches at colliders as well as for its consideration as a dark matter candidate and for the composition of neutron stars.
    Materialart: Online-Ressource
    ISSN: 0217-751X , 1793-656X
    RVK:
    Sprache: Englisch
    Verlag: World Scientific Pub Co Pte Ltd
    Publikationsdatum: 2021
    SSG: 16,12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Online-Ressource
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    MDPI AG ; 2019
    In:  Universe Vol. 5, No. 3 ( 2019-03-05), p. 69-
    In: Universe, MDPI AG, Vol. 5, No. 3 ( 2019-03-05), p. 69-
    Kurzfassung: Evolution of directed flow of charged particles produced in relativistic heavy-ion collisions at energies 4 ≤ s ≤ 19.6 GeV is considered within two microscopic transport models, ultra-relativistic quantum molecular dynamics (UrQMD) and quark-gluon string model (QGSM). In both models, the directed flow of protons changes its sign at midrapidity from antiflow to normal flow with decreasing energy of collisions, whereas the flows of mesons and antiprotons remain antiflow-oriented. For lighter colliding systems, such as Cu+Cu or S+S, changing of the proton directed flow occurs at lower bombarding energies and for more central topologies compared to a heavy Au+Au system. The differences can be explained by dissimilar production zones of different hadrons and by the influence of spectators. Directed flows of most abundant hadronic species at midrapidity are found to be formed within t = 10–12 fm/c after the beginning of nuclear collision. The influence of hard and soft mean-field potentials on the directed flow is also studied.
    Materialart: Online-Ressource
    ISSN: 2218-1997
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2019
    ZDB Id: 2813994-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
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    World Scientific Pub Co Pte Ltd ; 2020
    In:  International Journal of Modern Physics E Vol. 29, No. 11 ( 2020-11), p. 2040010-
    In: International Journal of Modern Physics E, World Scientific Pub Co Pte Ltd, Vol. 29, No. 11 ( 2020-11), p. 2040010-
    Kurzfassung: Here, we present new results obtained for the equation of state with induced surface and curvature tensions. The explicit formulas for the first five virial coefficients of system pressure and for the induced surface and curvature tension coefficients are derived and their possible applications are briefly discussed.
    Materialart: Online-Ressource
    ISSN: 0218-3013 , 1793-6608
    Sprache: Englisch
    Verlag: World Scientific Pub Co Pte Ltd
    Publikationsdatum: 2020
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Online-Ressource
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    MDPI AG ; 2022
    In:  Symmetry Vol. 14, No. 4 ( 2022-03-22), p. 634-
    In: Symmetry, MDPI AG, Vol. 14, No. 4 ( 2022-03-22), p. 634-
    Kurzfassung: We calculated the shear viscosity of hot and dense nuclear matter produced in a symmetric system of central gold–gold collisions at energies of BES RHIC, FAIR and NICA. For calculations of the collisions, the transport model UrQMD was employed. The shear viscosity was obtained within the Green–Kubo formalism. The hadron resonance gas model was used to determine temperature and chemical potentials of baryon charge and strangeness out of microscopic model calculations. In contrast to our previous works, we determined the partial viscosity of the main hadron species, such as nucleons, pions, kaons and Lambdas, via the nucleon–nucleon, pion–pion and so forth, correlators. A decrease in the beam energy from Elab=40 to 10 AGeV leads a to rise in baryon shear viscosity accompanied by a drop in the shear viscosity of mesons. The ratio of total shear viscosity to entropy density also decreases.
    Materialart: Online-Ressource
    ISSN: 2073-8994
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2518382-5
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Online-Ressource
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    MDPI AG ; 2021
    In:  Symmetry Vol. 13, No. 10 ( 2021-10-03), p. 1852-
    In: Symmetry, MDPI AG, Vol. 13, No. 10 ( 2021-10-03), p. 1852-
    Kurzfassung: This paper investigates the symmetry breaking between the polarizations of Λ and Λ¯ hyperons in relativistic collisions of heavy ions at intermediate and low energies. The microscopic transport model UrQMD is employed to study the thermal vorticity of hot and dense nuclear matter formed in non-central Au + Au collisions at center-of-mass energies 7.7≤sNN≤62.4 GeV. The whole volume of an expanding fireball is subdivided into small cubic cells. Then, we trace the final Λ and Λ¯ hyperons back to their last interaction point within a certain cell. Extracting the bulk parameters, such as energy density, net baryon density, and net strangeness of the hot and dense medium in the cell, one can obtain the cell temperature and the chemical potentials at the time of the hyperon emission. To do this, the extracted characteristics have to be fitted to the statistical model (SM) of ideal hadron gas. After that, the vorticity of nuclear matter and polarization of both hyperons are calculated. We found that the polarization of both Λ and Λ¯ increases with decreasing energy of heavy-ion collisions. The stronger polarization of Λ¯ is explained by (i) the slightly different freeze-out conditions of both hyperons and (ii) the different space–time distributions of Λ and Λ¯.
    Materialart: Online-Ressource
    ISSN: 2073-8994
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2021
    ZDB Id: 2518382-5
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Online-Ressource
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    MDPI AG ; 2023
    In:  Particles Vol. 6, No. 3 ( 2023-09-14), p. 864-875
    In: Particles, MDPI AG, Vol. 6, No. 3 ( 2023-09-14), p. 864-875
    Kurzfassung: The entropy produced by Unruh radiation is estimated and compared to the entropy of a Schwarzschild black hole. We simulate a spherical system of mass M by a set of Unruh horizons and estimate the total entropy of the outgoing radiation. Dependence on the mass and spin of the emitted particles is taken into account. The obtained results can be easily extended to any other intrinsic degrees of freedom of outgoing particles. The ratio of Unruh entropy to the Schwarzschild black hole entropy is derived in exact analytical form. For large black holes, this ratio exhibits high susceptibility to quantum numbers, e.g., spin s, of emitted quanta and varies from 0% for s=0 to 19.0% for s=5/2.
    Materialart: Online-Ressource
    ISSN: 2571-712X
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2023
    ZDB Id: 2926939-8
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Online-Ressource
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    EDP Sciences ; 2018
    In:  EPJ Web of Conferences Vol. 182 ( 2018), p. 02124-
    In: EPJ Web of Conferences, EDP Sciences, Vol. 182 ( 2018), p. 02124-
    Kurzfassung: We apply the idea of the Unruh effect to the description of particle production in relativistic heavy ion collisions. Because the full information about all particles is needed, we employ the spectra of hadrons generated by the UrQMD model for pp and Au+Au collisions at various energies. Particles are considered as generated straight at the Unruh horizon thus allowing estimation of the Unruh temperature of the source. The analysis is provided for different types of mesons and their charges.
    Materialart: Online-Ressource
    ISSN: 2100-014X
    Sprache: Englisch
    Verlag: EDP Sciences
    Publikationsdatum: 2018
    ZDB Id: 2595425-8
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Online-Ressource
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    MDPI AG ; 2022
    In:  Particles Vol. 5, No. 2 ( 2022-05-27), p. 157-170
    In: Particles, MDPI AG, Vol. 5, No. 2 ( 2022-05-27), p. 157-170
    Kurzfassung: The Unruh effect can be considered a source of particle production. The idea has been widely employed in order to explain multiparticle production in hadronic and heavy-ion collisions at ultrarelativistic energies. The attractive feature of the application of the Unruh effect as a possible mechanism of the multiparticle production is the thermalized spectra of newly produced particles. In the present paper, the total entropy generated by the Unruh effect is calculated within the framework of information theory. In contrast to previous studies, here the calculations are conducted for the finite time of existence of the non-inertial reference frame. In this case, only a finite number of particles are produced. The dependence on the mass of the emitted particles is taken into account. Analytic expression for the entropy of radiated boson and fermion spectra is derived. We study also its asymptotics corresponding to low- and high-acceleration limiting cases. The obtained results can be further generalized to other intrinsic degrees of freedom of the emitted particles, such as spin and electric charge.
    Materialart: Online-Ressource
    ISSN: 2571-712X
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2926939-8
    Standort Signatur Einschränkungen Verfügbarkeit
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