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Nuclear Theory·nucl-th

Thursday·April 16, 2020

11 papers—5 primary·6 cross-listed

All11Primary5Cross-lists6
  1. 01

    [Submitted on 15 Apr 2020]

    The possibility of twin star solutions in a model based on lattice QCD thermodynamics

    P. Jakobus🇦🇺 · A. Motornenko🇩🇪 · R. O. Gomes🇩🇪 · J. Steinheimer🇩🇪 · H. Stoecker🇩🇪

    The properties of compact stars and in particular the existence of twin star solutions are investigated within an effective model that is constrained by lattice QCD thermodynamics. The model is modified at large baryon densities to incorporate a large variety of scenarios of first order phase transitions to a phase of deconfined quarks. This is achieved by matching two different variants of the bag model equation of state, in order to estimate the role of the Bag model parameters on the appearance of a second family of neutron stars. The produced sequences of neutron stars are compared with modern constrains on stellar masses, radii, and tidal deformability from astrophysical observations and gravitational wave analyses. It is found that most of the possible scenarios disfavor a strong phase transition to quark matter and do not support the conjecture of a second family of neutron stars.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    2004.07026 [pdf]
    EPJC(2021)·31 citations
  2. 02

    [Submitted on 15 Apr 2020]

    Production of light nuclei at colliders -- coalescence vs. thermal model

    Stanislaw Mrowczynski🇵🇱

    The production of light nuclei in relativistic heavy-ion collisions is well described by both the thermal model, where light nuclei are in equilibrium with hadrons of all species present in a fireball, and by the coalescence model, where light nuclei are formed due to final-state interactions after the fireball decays. We present and critically discuss the two models and further on we consider two proposals to falsify one of the models. The first proposal is to measure a yield of exotic nuclide and compare it to that of . The ratio of yields of the nuclides is quite different in the thermal and coalescence models. The second proposal is to measure a hadron-deuteron correlation function which carries information whether a deuteron is emitted from a fireball together with all other hadrons, as assumed in the thermal model, or a deuteron is formed only after nucleons are emitted, as in the coalescence model. The correlation function is of interest in context of both proposals: it is needed to obtain the yield of which decays into and , but the correlation function can also tell us about an origin of .

    Comments:
    24 pages, 5 figures, final version as in the special volume `Strong Correlations in Dense Matter Physics' of the European Physical Journal ST. arXiv admin note: substantial text overlap with arXiv:2001.11351
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2004.07029 [pdf]
    Eur.Phys.J.ST(2020)·43 citations
  3. 03

    [Submitted on 14 Apr 2020]

    Influence of centrality definition and detector efficiency on the net-proton kurtosis

    Sukanya Sombun🇹🇭 · Jan Steinheimer🇩🇪 · Christoph Herold🇹🇭 · Ayut Limphirat🇹🇭 · Yupeng Yan🇹🇭 · Marcus Bleicher🇩🇪

    We study the influence of the centrality definition and detector efficiency on the net-proton kurtosis for minimum bias Au+Au collisions at a beam energy of GeV by using the UrQMD model. We find that different ways of defining the centrality lead to different cumulant ratios. Moreover, we demonstrate that the kurtosis is suppressed for central collisions when a wider transverse momentum acceptance is used. Finally, the influence of a detector efficiency on the measured cumulant ratios is estimated.

    Comments:
    9 pages, 5 figure
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2004.07040 [pdf]
    Springer Proc.Phys.(2020)·0 citations
  4. 04

    [Submitted on 23 Mar 2020]

    Application of Boltzmann equation to investigate kinetic processes of meson and baryon production in the quark-gluon plasma

    Yuriy Ostapov🇺🇦

    We consider the meson and baryon production in the quark-gluon plasma as applied to the early Universe and ultrarelativistic heavy ion collisions in collider. The essential feature of our investigation is to take into account a potential barrier for quarks under meson and baryon production. We have used the Boltzmann equation to describe kinetic processes of quark fusion. We have derived analytic expressions for solutions of kinetic equations. This permits to find the dependence of reaction rate on a time, temperature, mass and charge of quarks as well as on a string tension connected with the confining potential. Next we have considered in detail the meson and baryon production for some concrete kinetic processes in collisions of ultrarelativistic heavy ions. Exactly the same results will be as well true for processes in expanding Universe

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
    arXiv:
    2004.07051 [pdf]
    0 citations
  5. 05

    [Submitted on 15 Apr 2020]

    How well do we know the neutron-matter equation of state at the densities inside neutron stars? A Bayesian approach with correlated uncertainties

    C. Drischler🇺🇸 · R. J. Furnstahl🇺🇸 · J. A. Melendez🇺🇸 · D. R. Phillips🇺🇸

    We introduce a new framework for quantifying correlated uncertainties of the infinite-matter equation of state derived from chiral effective field theory (EFT). Bayesian machine learning via Gaussian processes with physics-based hyperparameters allows us to efficiently quantify and propagate theoretical uncertainties of the equation of state, such as EFT truncation errors, to derived quantities. We apply this framework to state-of-the-art many-body perturbation theory calculations with nucleon-nucleon and three-nucleon interactions up to fourth order in the EFT expansion. This produces the first statistically robust uncertainty estimates for key quantities of neutron stars. We give results up to twice nuclear saturation density for the energy per particle, pressure, and speed of sound of neutron matter, as well as for the nuclear symmetry energy and its derivative. At nuclear saturation density the predicted symmetry energy and its slope are consistent with experimental constraints.

    Comments:
    7 pages, 2 figures, supplemental material; close to the published version; minor corrections and additional discussion of correlations in supplemental material; Jupyter notebooks for reproducing the results and figures can be found at https://buqeye.github.io/software/
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2004.07232 [pdf]
    PRL(2020)·349 citations

Affiliations

first authorsco-authorsvia INSPIRE