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Nuclear Theory·nucl-th

Wednesday·December 13, 2023

14 papers—7 primary·7 cross-listed

All14Primary7Cross-lists7
  1. 08

    Constraining nucleon effective masses with flow and stopping observables from the SRIT experiment

    C.Y. Tsang · M. Kurata-Nishimura · M.B. Tsang · W.G. Lynch · Y.X. Zhang · J. Barney · J. Estee · G. Jhang · R. Wang · M. Kaneko · J.W. Lee · T. Isobe and 43 other authors

    Properties of the nuclear equation of state (EoS) can be probed by measuring the dynamical properties of nucleus-nucleus collisions. In this study, we present the directed flow (), elliptic flow () and stopping (VarXZ) measured in fixed target Sn + Sn collisions at 270 AMeV with the SRIT Time Projection Chamber. We perform Bayesian analyses in which EoS parameters are varied simultaneously within the Improved Quantum Molecular Dynamics-Skyrme (ImQMD-Sky) transport code to obtain a multivariate correlated constraint. The varied parameters include symmetry energy, , and slope of the symmetry energy, , at saturation density, isoscalar effective mass, , isovector effective mass, and the in-medium cross-section enhancement factor . We find that the flow and VarXZ observables are sensitive to the splitting of proton and neutron effective masses and the in-medium cross-section. Comparisons of ImQMD-Sky predictions to the SRIT data suggest a narrow range of preferred values for , and .

    ↳ nucl-exnucl-thPLB(2024)·17 citations
  2. 09

    Element abundance patterns in stars indicate fission of nuclei heavier than uranium

    Ian U. Roederer · Nicole Vassh · Erika M. Holmbeck · Matthew R. Mumpower · Rebecca Surman · John J. Cowan · Timothy C. Beers · Rana Ezzeddine · Anna Frebel · Terese T. Hansen · Vinicius M. Placco · Charli M. Sakari

    The heaviest chemical elements are naturally produced by the rapid neutron-capture process (r-process) during neutron star mergers or supernovae. The r-process production of elements heavier than uranium (transuranic nuclei) is poorly understood and inaccessible to experiments, so must be extrapolated using nucleosynthesis models. We examine element abundances in a sample of stars that are enhanced in r-process elements. The abundances of elements Ru, Rh, Pd, and Ag (atomic numbers Z = 44 to 47, mass numbers A = 99 to 110) correlate with those of heavier elements (63 <= Z <= 78, A > 150). There is no correlation for neighboring elements (34 <= Z <= 42 and 48 <= Z <= 62). We interpret this as evidence that fission fragments of transuranic nuclei contribute to the abundances. Our results indicate that neutron-rich nuclei with mass numbers >260 are produced in r-process events.

    ↳ astro-ph.SRastro-ph.GAastro-ph.HEnucl-ex+1Science(2023)·19 citations
  3. 10

    On the QCD critical point, Lee-Yang edge singularities and Pade resummations

    Gokce Basar🇺🇸

    We analyze the trajectory of the Lee-Yang edge singularities of the QCD equation of state in the complex baryon chemical potential () plane for different values of the temperature by using the recent lattice results for the Taylor expansion coefficients up to eighth order in and various resummation techniques that blend in Pade expansions and conformal maps. By extrapolating from this information, we estimate for the location of the QCD critical point, MeV, MeV. We also estimate the crossover slope at the critical point to be and further constrain the non-universal mapping parameters between the three dimensional Ising model and QCD equations of state.

    ↳ hep-thnucl-thPRC(2024)·86 citations
  4. 11

    Hybrid stars in light of the HESS J1731-347 remnant and the PREX-II experiment

    P. Laskos-Patkos🇬🇷 · P.S. Koliogiannis🇬🇷 · Ch.C. Moustakidis🇬🇷

    The recent analysis on the central compact object in the HESS J1731-347 remnant suggests interestingly small values for its mass and radius. Such an observation favors soft nuclear models that may be challenged by the observation of massive compact stars. In contrast, the recent PREX-II experiment, concerning the neutron skin thickness of Pb, points towards stiff equations of state that favor larger compact star radii. In the present study, we aim to explore the compatibility between stiff hadronic equations of state (favored by PREX-II) and the HESS J1731-347 remnant in the context of hybrid stars. For the construction of hybrid equations of state we use three widely employed Skyrme models combined with the well-known vector MIT bag model. Furthermore we consider two different scenarios concerning the energy density of the bag. In the first case, that of a constant bag parameter, we find that the resulting hybrid equations of state are strongly disfavored by the observation of pulsars. However, the introduction of a Gaussian density dependence yields results that are compatible with the conservative constraint. The utilization of recent data based on the observation of PSR J0030+0451, PSR J0952-0607 and GW190814 allows for the imposition of additional constraints on the relevant parameters and the stiffness of the two phases. Interestingly, we find that the derived hybrid equations of state do not satisfy the PSR J0030+0451 constraints in and only marginally agree with the estimations. In addition, we estimate that the observation of massive pulsars, like PSR J0952-0607, in combination with the existence of HESS J1731-347, may require a strong phase transition below . Finally, we show that the supermassive compact object involved in GW190814 could potentially be explained as a rapidly rotating hybrid star.

    ↳ astro-ph.HEgr-qcnucl-thPRD(2024)·39 citations
  5. 12

    Supramassive dark objects with neutron star origin

    M. Vikiaris🇬🇷 · V. Petousis🇨🇿 · M. Veselsky🇨🇿 · Ch.C. Moustakidis🇬🇷

    Till today, the nature of Dark Matter (DM) remains elusive despite all our efforts. This missing matter of the universe has not been observed by the already operating DM direct-detection experiments, but we can infer its gravitational effects. Galaxies and clusters of galaxies are most likely to contain DM trapped to their gravitational field. This leads us to the natural assumption that compact objects might contain DM too. Among the compact objects exist in galaxies, neutron stars are considered as natural laboratories, where theories can be tested, and observational data can be received. Thus, many models of DM have proposed it's presence in those stars. In particular, in the present study we focus on two types of dark matter particles, namely fermions and bosons with a mass range of [0.01-1.5] GeV and self-interaction strength in the range [10-10] MeV. By employing the two-fluid model, we discovered a stable area in the M-R diagram of a celestial formation consisting of neutron star matter and DM that is substantial in size. This formation spans hundreds of kilometers in diameter and possesses a mass equivalent to 100 or more times the Solar mass. To elucidate, this entity resembles an enormous celestial body of DM, with a neutron star at its core. This implies that a supramassive stellar compact entity can exist without encountering any issues of stability and without undergoing a collapse into a black hole. In any case, the present theoretical prediction can, if combined with corresponding observations, shed light on the existence of DM and even more on its basic properties.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAgr-qc+2PRD(2024)·12 citations
  6. 13

    Influence of baryon number, strangeness, and electric charge fluctuations at the LHC

    Christopher Plumberg🇺🇸 · Dekrayat Almaalol🇺🇸 · Travis Dore🇩🇪 · Jordi Salinas San Martin🇺🇸 · Patrick Carzon🇺🇸 · Debora Mroczek🇺🇸 · Nanxi Yao🇺🇸 · Willian M. Serenone🇺🇸 · Lydia Spychalla🇺🇸 · Matthew Sievert🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸

    At the Large Hadron Collider it is possible to generate BSQ (baryon, strangeness, and electric) charge density fluctuations from gluon splittings into quark/anti-quark pairs, generated within the ICCING model. In this work, we implement BSQ charge dynamics in a fully integrated framework. We propagate these conserved charges within an upgraded version of the v-USPhydro hydrodynamic model, which conserves the BSQ densities exactly. Our hydrodynamic simulation uses the full 4D equation of state from lattice Quantum Chromodynamics and includes decays from the Particle Data Group 2016+. We study the dynamical trajectories of fluid cells passing through the QCD phase diagram. We discuss future applications for this new framework.

    ↳ hep-phnucl-exnucl-th5 citations
  7. 14

    Small-x structure of oxygen and neon isotopes as seen by the Large Hadron Collider

    Giuliano Giacalone🇫🇮 · Bjoern Schenke🇩🇪 · Soeren Schlichting🇺🇸 · Pragya Singh🇩🇪

    Results on collisions of O nuclei performed at the Relativistic Heavy Ion Collider (RHIC) have been presented for the first time at Quark Matter 2023 by the STAR collaboration. O+O collisions are also expected to take place in the near future at the Large Hadron Collider (LHC) at much higher beam energies. We explore the potential of beam-energy-dependent studies for this system to probe small- dynamics and QCD evolution. We perform 3+1D IP-Glasma simulations to predict the rapidity dependence of the initial geometry of light-ion collisions, focusing on O+O and Ne+Ne collisions at GeV and 7 TeV. The choice of Ne is motivated by its strongly elongated geometry, which may respond differently to the effect of the high-energy evolution compared to the more spherical O. We find that smearing induced by soft gluon production at high energy causes mild variations in the initial-state eccentricities as a function of the collision energy. These effects could be resolved in future experiments and deserve further investigation.

    ↳ hep-phnucl-thEPJ Web Conf.(2024)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE