Nuclear Theory·nucl-th

Monday·November 18, 2019

9 papers—4 primary·5 cross-listed

01
Primary fission fragment mass yields across the chart of nuclides
M. R. Mumpower · P. Jaffke · M. Verriere · J. Randrup
We have calculated a complete set of primary fission fragment mass yields, $Y (A)$ , for heavy nuclei across the chart of nuclides, including those of particular relevance to the rapid neutron capture process ( $r$ process) of nucleosynthesis. We assume that the nuclear shape dynamics are strongly damped which allows for a description of the fission process via Brownian shape motion across nuclear potential-energy surfaces. The macroscopic energy of the potential was obtained with the Finite-Range Liquid-Drop Model (FRLDM), while the microscopic terms were extracted from the single-particle level spectra in the fissioning system by the Strutinsky procedure for the shell energies and the BCS treatment for the pairing energies. For each nucleus considered, the fission fragment mass yield, $Y (A)$ , is obtained from 50,000 -- 500,000 random walks on the appropriate potential-energy surface. The full mass and charge yield, $Y (Z, A)$ , is then calculated by invoking the Wahl systematics. With this method, we have calculated a comprehensive set of fission-fragment yields from over 3,800 nuclides bounded by $80 \leq Z \leq 130$ and $A \leq 330$ ; these yields are provided as an ASCII formatted database in the supplemental material. We compare our yields to known data and discuss general trends that emerge in low-energy fission yields across the chart of nuclides.
nucl-thastro-ph.SRPRC(2020)·71 citations
02
Equation of state of QCD matter within the Hagedorn bag-like model
Volodymyr Vovchenko🇩🇪 · Mark I. Gorenstein🇩🇪 · Carsten Greiner🇩🇪 · Horst Stoecker🇩🇪
The QCD equation of state at finite temperature and densities of conserved charges is considered in the framework of a Hagedorn bag-like model, incorporating both the finite sizes of hadrons as well as their exponential mass spectrum. Augmented with non-zero masses of quarks and gluons in the bag spectrum, the model yields a fair quantitative description of lattice data on thermodynamic functions, the conserved charges susceptibilities, and Fourier coefficients of net-baryon density. Both at zero and finite baryon densities a broad crossover transition between hadronic and quark-gluon matter is observed. The model thus provides a thermodynamically consistent construction of a crossover equation of state for finite baryon number, electric charge and strangeness chemical potentials, which can be used in fluid dynamical simulations of heavy-ion collisions.
nucl-thhep-phSpringer Proc.Phys.(2020)·2 citations
03
Ab-initio no-core Gamow shell model calculations of multi-neutron systems
Jian Guo Li · Nicolas Michel · Bai Shan Hu · Wei Zuo · Fu Rong Xu
The existence of multi-neutron systems has always been a debatable question. Indeed, both inter-nucleon correlations and a large continuum coupling occur in these states. We then employ the ab-initio no-core Gamow shell model to calculate the resonant energies and widths of the trineutron and tetraneutron systems with realistic interactions. Our results indicate that trineutron and tetraneutron are both unbound and bear broad widths. The calculated energy and width of tetraneutron are also comparable with recent experimental data. Moreover, our calculations suggest that the energy of trineutron is lower than that of tetraneutron, while its resonance width is also narrower. This strongly suggests that trineutron is more likely to be experimentally observed than tetraneutron. We thus suggest experimentalists to search for trineutron at low energy.
nucl-thPRC(2019)·71 citations
04
Longitudinal dependence of open heavy flavor $R_{AA}$ in relativistic heavy-ion collisions
Caio A. G. Prado🇨🇳 · Wen-Jing Xing🇨🇳 · Shanshan Cao🇺🇸 · Guang-You Qin🇨🇳 · Xin-Nian Wang🇨🇳
Heavy flavor probes are sensitive to the properties of the quark gluon plasma (QGP) produced in relativistic heavy-ion collisions. A huge amount of effort has been devoted to studying different aspects of the heavy-ion collisions using heavy flavor particles. In this work, we study the dynamics of heavy quark transport in the QGP medium using the rapidity dependence of heavy flavor observables. We calculate the nuclear modification of $B$ and $D$ meson spectra as well as spectra of leptons from heavy flavor decays in the rapidity range $[- 4.0, 4.0]$ . We use an implementation of the improved Langevin equation with gluon radiation on top of a (3+1)-dimensional relativistic viscous hydrodynamical background for several collision setups. We find that the rapidity dependence of the heavy quark modification is determined by the interplay between the smaller size of the medium, which affects the path length of the heavy quarks, and the softer heavy quark initial production spectrum. We compare our results with available experimental data and present predictions for open heavy flavor meson $R_{AA}$ at finite rapidity.
nucl-thhep-exhep-phPRC(2020)·9 citations
05
Quantum Computing for Neutrino-nucleus Scattering
Alessandro Roggero🇺🇸 · Andy C. Y. Li🇺🇸 · Joseph Carlson🇺🇸 · Rajan Gupta🇺🇸 · Gabriel N. Perdue🇺🇸
Neutrino-nucleus cross section uncertainties are expected to be a dominant systematic in future accelerator neutrino experiments. The cross sections are determined by the linear response of the nucleus to the weak interactions of the neutrino, and are dominated by energy and distance scales of the order of the separation between nucleons in the nucleus. These response functions are potentially an important early physics application of quantum computers. Here we present an analysis of the resources required and their expected scaling for scattering cross section calculations. We also examine simple small-scale neutrino-nucleus models on modern quantum hardware. In this paper, we use variational methods to obtain the ground state of a three nucleon system (the triton) and then implement the relevant time evolution. In order to tame the errors in present-day NISQ devices, we explore the use of different error-mitigation techniques to increase the fidelity of the calculations.
↳ quant-phhep-lathep-phnucl-thPRD(2020)·112 citations
06
Global flow structure and exact formal transseries of the Gubser flow in kinetic theory
Alireza Behtash🇺🇸 · Syo Kamata🇺🇸 · Mauricio Martinez🇺🇸 · Haosheng Shi🇺🇸
In this work we introduce the generic conditions for the existence of a non-equilibrium attractor that is an invariant manifold determined by the long-wavelength modes of the physical system. We investigate the topological properties of the global flow structure of the Gubser flow for the Israel-Stewart theory and a kinetic model for the Boltzmann equation by employing Morse-Smale theory. We present a complete classification of the invariant submanifolds of the flow and determine all the possible flow lines connecting any pair of UV/IR fixed points. The formal transseries solutions to the Gubser dynamical system around the early-time (UV) and late-time (IR) fixed points are constructed and analyzed. It is proven that these solutions are purely perturbative (or power-law asymptotic) series with a finite radius of convergence. Based on these analyses, we find that Gubser-like expanding kinetic systems do not hydrodynamize owing to the failure of the hydrodynamization process which heavily relies on the classification of (non)hydrodynamic modes in the IR regime. This is in contrast to longitudinal boost-invariant plasmas where the asymptotic dynamics is described by a few terms of the hydrodynamic gradient expansion. We finally compare our results for both Bjorken and Gubser conformal kinetic models.
↳ hep-thnucl-thJHEP(2020)·40 citations
07
Role of the $Λ (1600)$ in the $K^{-} p \to Λ π^{0} π^{0}$ reaction
He Zhou🇨🇳 · Ju-Jun Xie🇨🇳
Role of the $Λ (1600)$ is studied in the $K^{-} p \to Λ π^{0} π^{0}$ reaction by using the effective Lagrangian approach near the threshold. We perform a calculation for the total and differential cross sections by considering the contributions from the $Λ (1600)$ and $Λ (1670)$ intermediate resonances decaying into $π^{0} Σ^{* 0} (1385)$ with $Σ^{* 0} (1385)$ decaying into $π^{0} Λ$ . Besides, the non-resonance process from $u$ -channel nucleon pole is also taken into account. With our model parameters, the current experimental data on the total cross sections of the $K^{-} p \to Λ π^{0} π^{0}$ reaction can be well reproduced. It is shown that we really need the contribution from the $Λ (1600)$ with spin-parity $J^{P} = 1/ 2^{+}$ , and that these measurements can be used to determine some of the properties of the $Λ (1600)$ resonance. Furthermore, we also plot the $π^{0} Λ$ invariant mass distributions which could be tested by the future experimental measurements.
↳ hep-phhep-exnucl-exnucl-thCommun.Theor.Phys.(2020)·2 citations
08
Cross-correlators of conserved charges in QCD
Rene Bellwied🇺🇸 · Szabolcs Borsanyi🇩🇪 · Zoltan Fodor🇩🇪 · Jana N. Guenther🇩🇪 · Jacquelyn Noronha-Hostler🇺🇸 · Paolo Parotto🇺🇸 · Attila Pasztor🇭🇺 · Claudia Ratti🇺🇸 · Jamie M. Stafford🇺🇸
We present cross-correlators of QCD conserved charges at $μ_{B} = 0$ from lattice simulations and perform a Hadron Resonance Gas (HRG) model analysis to break down the hadronic contributions to these correlators. We construct a suitable hadronic proxy for the ratio $- χ_{11}^{B S} / χ_{2}^{S}$ and discuss the dependence on the chemical potential and experimental cuts. We then perform a comparison to preliminary STAR results and comment on a possible direct comparison of lattice and experiment.
↳ hep-phhep-latnucl-thSpringer Proc.Phys.(2020)·0 citations
09
Lifetimes and moments measurements to investigate the structure of midheavy nuclei
T.J. Mertzimekis · A. Khaliel · D. Papaioannou · G. Zagoraios · A. Zyriliou
Mid-heavy nuclei offer unique opportunities to study the collective and single-particle aspects of nuclear structure. This mass regime is a dynamic area where protons and neutrons generally occupy different orbitals, giving rise to complex structures with a wide variety of shapes, shape evolution and shape coexistence. To that end, measurements of nuclear lifetimes and electromagnetic moments ( $μ$ , $Q$ ) can be invaluable. Recent experimental activities of the NuSTRAP group in Athens have focused on $γ$ -spectroscopy studies employing the RoSPHERE array in Magurele, Romania. In recent studies [1,2], the neutron-rich $^{144 - 146}$ Ba isotopes have exhibited octupole degrees of freedom. Similar questions exist for the lighter $^{140}$ Ba isotope, which is located at the onset of octupole collectivity. In addition, understanding the structure of heavier, even-even hafnium isotopes requires more data regarding shape coexistence and shape evolution. Preliminary results on lifetimes in this area pave the way to understand dynamical phenomena prior to studying more exotic species in the future.
↳ nucl-exnucl-thBulg.J.Phys.(2019)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE