Nuclear Theory·nucl-th
12 papers—3 primary·9 cross-listed
Quantum fluctuation expression of the baryon number for a subsystem consisting of hot relativistic spin- particles are derived. These fluctuations seems to diverge in the limit where system size goes to zero. For a broad range of thermodynamic parameters numerical solutions are obtained which might be helpful to interpret the heavy-ion experimental data.
Vadim Lensky🇩🇪 · Astrid Hiller Blin🇺🇸 · Vladimir Pascalutsa🇩🇪
We calculate the forward unpolarised doubly-virtual Compton scattering (VVCS) off the deuteron in the framework of pionless effective field theory, up to next-to-next-to-next-to-leading order (N3LO) for the longitudinal and next-to-leading order (NLO) for the transverse amplitude. The charge elastic form factor of the deuteron, obtained from the residue of the longitudinal VVCS amplitude, is used to extract the value of the single unknown two-nucleon one-photon contact coupling that enters the longitudinal amplitude at N3LO. We also study the lowest spin-independent generalised polarisabilities of the deuteron. The calculated unpolarised VVCS amplitude provides a high-precision model-independent input for a future calculation of the two-photon-exchange correction to the Lamb shift of muonic deuterium.
To describe the yrast states in weakly bound nuclei, I directly solve the coordinate-space cranked Skyrme-Hartree-Fock-Bogoliubov equation on a three-dimensional lattice with the continuum states discretized in a box. After the numerical demonstration for the ground-state band in a medium-mass nucleus, I apply the newly-developed method to neutron-rich even- Mg isotopes. I find that the appearance of the significantly low state in Mg is mainly due to the suppression of pairing. The calculation predicts that the state in Mg appears as high in energy as in Mg whereas the triaxial deformation is enhanced in non-zero spin states. The present numerical framework offers a practical approach for investigating the near yrast states systematically and revealing structures unique in drip-line nuclei.
A chronicle describing the historical context and the development of ideas and experiments leading to the discovery of the back-bending phenomenon in rapidly rotating atomic nuclei some 50 years ago is presented. The moment of inertia of some atomic nuclei increases anomalously at a certain rotational frequency, revealing important clues to our understanding of nuclear structure. I highlight the decisive interactions and contacts between experimentalists and theorists, which created the right environment, allowing for the revelation of an undetected phenomenon in Nature. Finally, I reflect on the key points allowing for the discovery and particularly point to the importance of systematic surveys, which in this case investigated the energy levels in heavy nuclei of a large sample of elements, as well as to the accuracy of the measurements of the ground state levels made at the time.
M. Vorabbi · G.P.A. Nobre · D.A. Brown · A.M. Lewis · E. Rubino · S. Mughabghab
The National Ignition Facility at Lawrence Livermore National Laboratory uses Kr as a diagnostic tool to measure the neutron flux produced by fusion reactions. As krypton is chemically inert, it can be implanted directly into the fuel capsule, and the reaction products can be measured to determine the flux of fusion neutrons. Kr cross sections also provide model constraints for the Kr branching point in the s-process and the neutron flux in stars. In this work, experimental data on the neutron production, radiative capture, inelastic scattering, and total cross sections of Kr were used in conjunction with the fast region nuclear reaction code EMPIRE and a new resonance-region evaluation to produce a new evaluation of neutron-induced reactions on Kr. For the EMPIRE calculations, we fitted the optical model potential up to 12 MeV to simultaneously reproduce the experimental data for the total cross section and the main inelastic gamma transition from the state to the ground state. For energies above 12 MeV, due to large fluctuations and uncertainties in the total cross section data, we preferred to adopt the Koning-Delaroche global spherical optical model potential. With these models and corrections to the structure of Kr, the evaluated cross sections matched the experimental data. The new evaluation has been submitted for incorporation in the next release of the ENDF/B nuclear reaction library.
Amanda L. Baxter · Segev BenZvi · Joahan Castaneda Jaimes · Alexis Coleiro · Marta Colomer Molla · Damien Dornic · Tomer Goldhagen · Anne M. Graf · Spencer Griswold · Alec Habig · Remington Hill · Shunsaku Horiuchi James P. Kneller Rafael F. Lang and 8 other authors
Current neutrino detectors will observe hundreds to thousands of neutrinos from a Galactic supernovae, and future detectors will increase this yield by an order of magnitude or more. With such a data set comes the potential for a huge increase in our understanding of the explosions of massive stars, nuclear physics under extreme conditions, and the properties of the neutrino. However, there is currently a large gap between supernova simulations and the corresponding signals in neutrino detectors, which will make any comparison between theory and observation very difficult. SNEWPY is an open-source software package which bridges this gap. The SNEWPY code can interface with supernova simulation data to generate from the model either a time series of neutrino spectral fluences at Earth, or the total time-integrated spectral fluence. Data from several hundred simulations of core-collapse, thermonuclear, and pair-instability supernovae is included in the package. This output may then be used by an event generator such as sntools or an event rate calculator such as SNOwGLoBES. Additional routines in the SNEWPY package automate the processing of the generated data through the SNOwGLoBES software and collate its output into the observable channels of each detector. In this paper we describe the contents of the package, the physics behind SNEWPY, the organization of the code, and provide examples of how to make use of its capabilities.
Juan M. Torres-Rincon🇩🇪 · Glòria Montaña🇪🇸 · Àngels Ramos🇪🇸 · Laura Tolos🇪🇸
We study the spectroscopy and transport properties of charmed mesons in a thermal medium by applying an effective field theory based on chiral and heavy-quark symmetries in the imaginary time formalism. Relying on unitarity constraints and self-consistency we extract the in-medium properties (masses and widths) of and mesons and their interactions with light hadrons. We report our findings on 1) dynamically generated states, 2) thermal evolution of chiral partners, 3) in-medium scattering amplitudes, and 4) transport coefficients below the chiral restoration temperature.
Arthur G Suvorov · Kostas Glampedakis
It is commonly believed that neutron stars exceeding the maximum mass limit for stability could be formed in the aftermath of binary neutron star mergers, enjoying a short life of metastability before losing centrifugal support and collapsing to a black hole. It is suggested here that a similar scenario could take place when the remnant's excess mass is supported by an ultra-strong magnetic field that could be generated during, and shortly after, coalescence. We show that such 'magnetically supramassive' neutron stars could stave off collapse and survive for a few years before their magnetic energy is sufficiently dissipated due to ambipolar diffusion. In addition, we speculate on multi-messenger signatures of such objects and discuss the robustness of our results against limitations placed by neutron superfluidity and magneto-thermal evolution.
In this paper we introduce the axial gauge field to the framework of the quantum kinetic theory with vector gauge field in the massless limit. Treating axial-gauge field on an equal footing with the vector-gauge field, we construct a consistent solution to the kinetic equations up to the first order in gradient expansion or equivalently the semi-classical expansion. The intuitive extension of quantum kinetic theory presented in this work provides a natural generalization, and turns out to give rise to the covariant anomaly and the covariant currents. The corresponding consistent currents can be obtained from the covariant ones by adding the Chern-Simons current. We use the consistent currents to calculate various correlation functions among currents and energy-momentum tensor in equilibrium state.
Roland Diehl · Maria Lugaro · Alexander Heger · Andre Sieverding · Xiaodong Tang · KuoAng Li · Ertao Li · Carolyn L. Doherty · Martin G.H. Krause · Anton Wallner · Nikos Prantzos · Hannah E. Brinkman and 6 other authors
The cosmic evolution of the chemical elements from the Big Bang to the present time is driven by nuclear fusion reactions inside stars and stellar explosions. A cycle of matter recurrently re-processes metal-enriched stellar ejecta into the next generation of stars. The study of cosmic nucleosynthesis and of this matter cycle requires the understanding of the physics of nuclear reactions, of the conditions at which the nuclear reactions are activated inside the stars and stellar explosions, of the stellar ejection mechanisms through winds and explosions, and of the transport of the ejecta towards the next cycle, from hot plasma to cold, star-forming gas. Due to the long timescales of stellar evolution, and because of the infrequent occurrence of stellar explosions, observational studies are challenging. Due to their radioactive lifetime of million years, the 26Al and 60Fe isotopes are suitable to characterise simultaneously the processes of nuclear fusion reactions and of interstellar transport. We describe and discuss the nuclear reactions involved in the production and destruction of 26Al and 60Fe, the key characteristics of the stellar sites of their nucleosynthesis and their interstellar journey after ejection from the nucleosynthesis sites. We connect the theoretical astrophysical aspects to the variety of astronomical messengers, from stardust and cosmic-ray composition measurements, through observation of gamma rays produced by radioactivity, to material deposited in deep-sea ocean crusts and to the inferred composition of the first solids that have formed in the Solar System. We show that considering measurements of the isotopic ratio of 26Al to 60Fe eliminate some of the unknowns when interpreting astronomical results, and discuss the lessons learned from these two isotopes on cosmic chemical evolution.
Anna Schäfer🇩🇪 · Iurii Karpenko🇨🇿 · Hannah Elfner🇩🇪
Heavy-ion collisions covering a wide range of collision energies provide a vast amount of observables characterizing the properties of strongly-interacting matter. In particular collisions towards the high baryon-density regime of the QCD phase-diagram have become of interest to study the postulated first order phase transition and to locate a possible critical end point. In this work, the SMASH-vHLLE-hybrid is presented as a novel hybrid model to theoretically describe such heavy-ion collisions. In addition, the SMASH hadron resonance gas equation of state is introduced. The accuracy of the latter is shown to be of fundamental importance in order to conserve energy, baryon number and electric charge throughout the different stages of the hybrid model. Furthermore, the impact of an inaccurate equation of state on final state observables is discussed. This work constitutes a first validation of the SMASH-vHLLE-hybrid in terms of conservation laws and excitation functions. It is expected to be applied to a broader range of observables in the future.
G. N. Zeminiani🇧🇷 · J. J. Cobos-Martínez🇲🇽 · K. Tsushima🇧🇷
[1]Abstract: This is a contribution for the PANIC 2021 Proceedings based on the articles, Eur. Phys. J. A 57, 259 (2021) and the accompanied article arXiv:2109.08636 hep-ph (Hadron 2021 contribution). We have estimated for the first time the mass shifts of the and mesons in symmetric nuclear matter by an SU(5) flavor symmetric effective Lagrangian approach, as well as the in-medium mass of meson by the quark-meson coupling (QMC) model. The attractive potentials for the - and -nuclear matter are obtained, and one can expect for these mesons to form nuclear bound states. We have indeed found such nuclear bound states with C nucleus, where the results for the C nucleus bound state energies are new, and we report here for the first time. [2]Abstract: We estimate for the first time the mass shifts (scalar potentials) in symmetric nuclear matter of the and mesons using an effective Lagrangian approach, as well as the in-medium mass of the meson by the quark-meson coupling model. The attractive potentials of both and are expected to be strong enough for these mesons to be bound to the He nucleus, and we have obtained such nuclear bound state energies.
first authorsco-authorsvia INSPIRE