Unified Equation of State for Neutron Stars Based on the Gogny Interaction

The effective Gogny interactions of the D1 family were established by D. Gogny more than forty years ago with the aim to describe simultaneously the mean field and the pairing field corresponding to the nuclear interaction. The most popular Gogny parametrizations, namely D1S, D1N and D1M, describe accurately the ground-state properties of spherical and deformed finite nuclei all across the mass table obtained with Hartree–Fock–Bogoliubov (HFB) calculations. However, these forces produce a rather soft equation of state (EoS) in neutron matter, which leads to predict maximum masses of neutron stars well below the observed value of two solar masses. To remove this limitation, we built new Gogny parametrizations by modifying the density dependence of the symmetry energy predicted by the force in such a way that they can be applied to the neutron star domain and can also reproduce the properties of finite nuclei as good as their predecessors. These new parametrizations allow us to obtain stiffer EoS’s based on the Gogny interactions, which predict maximum masses of neutron stars around two solar masses. Moreover, other global properties of the star, such as the moment of inertia and the tidal deformability, are in harmony with those obtained with other well tested EoSs based on the SLy4 Skyrme force or the Barcelona–Catania–Paris–Madrid (BCPM) energy density functional. Properties of the core-crust transition predicted by these Gogny EoSs are also analyzed. Using these new Gogny forces, the EoS in the inner crust is obtained with the Wigner–Seitz approximation in the Variational Wigner–Kirkwood approach along with the Strutinsky integral method, which allows one to estimate in a perturbative way the proton shell and pairing corrections. For the outer crust, the EoS is determined basically by the nuclear masses, which are taken from the experiments, wherever they are available, or by HFB calculations performed with these new forces if the experimental masses are not known.

Fission in a microscopic framework: From basic science to support for applications

Recent developments, both in theoretical modeling and computational power, have allowed us to make progress on a goal not fully achieved yet in nuclear theory: a microscopic theory of nuclear fission. Even if the complete microscopic description remains a computationally demanding task, the information that can be provided by current calculations can be extremely useful to guide and constrain more phenomenological approaches, which are simpler to implement. First, a microscopic model that describes the real-time dynamics of the fissioning system can justify or rule out some of the approximations. Second, the microscopic approach can be used to obtain trends, e.g., with increasing excitation energy of the fissioning system, or even to compute observables that cannot be otherwise calculated in phenomenological approaches or that can be hindered by the limitations of the method. We briefly present in this contribution the time-dependent superfluid local density approximation (TDSLDA) approach to nuclear fission, approach that has become a very successful theoretical model in many areas of many-body research. The TDSLDA incorporates the effects of the continuum, the dynamics of the pairing field, and the numerical solution is implemented with controlled approximations and negligible numerical errors. The main part of the current contribution will be dedicated to discussing the method, and recent results concerning the fission dynamics. In addition, we present results on the excitation energy sharing between the fragments, which are in agreement with a qualitative conclusions extracted from a limited number of experimental measurements of properties of prompt neutrons.

Superconducting optical response of photodoped Mott insulators

Ultrafast laser pulses can redistribute charges in Mott insulators on extremely short time scales, leading to the fast generation of photocarriers. It has recently been demonstrated that these photocarriers can form a novel [Formula: see text]-paired condensate at low temperatures, featuring a staggered superconducting pairing field. In this conference paper, we discuss the origin of the [Formula: see text]-paired hidden phase and its optical response, which may be detected in a pump-probe experiment. The hidden phase may be relevant for possible light-induced superconductivity in Mott insulators.

Quantifying surface severity of the 2014 and 2015 fires in the Great Slave Lake area of Canada

The focus of this paper was the development of surface organic layer severity maps for the 2014 and 2015 fires in the Great Slave Lake area of the Northwest Territories and Alberta, Canada, using multiple linear regression models generated from pairing field data with Landsat 8 data. Field severity data were collected at 90 sites across the region, together with other site metrics, in order to develop a mapping approach for surface severity, an important metric for assessing carbon loss from fire. The approach utilised a combination of remote sensing indices to build a predictive model of severity that was applied within burn perimeters. Separate models were created for burns in the Shield and Plain ecoregions using spectral data from Landsat 8. The final Shield and Plain models resulted in estimates of surface severity with 0.74 variance explained (R2) for the Plain ecoregions and 0.67 for the Shield. The 2014 fires in the Plain ecoregion were more severe than the 2015 fires and fires in both years in the Shield ecoregion. In further analysis of the field data, an assessment of relationships between surface severity and other site-level severity metrics found mixed results.

Pairing corrections within the density-dependent delta interaction

The validity of the Strutinsky prescriptions is tested within a state-dependent pairing interaction instead of a constant pairing strength. The amplitude of the pairing field is determined to reproduce the experimental values of the pairing gaps in the ground state of the parent [Formula: see text]Th. The density-dependent delta interaction was used to compute the quantities related to the pairing corrections along a fission trajectory, such as Fermi energies, pairing gaps, and pairing effects. An enhancement of the pairing gaps during the penetration of the second barrier was evidenced in the case of the state-dependent pairing formalism. Moreover, the outer barrier calculated in the framework of the macroscopic–microscopic model is strongly suppressed.

PROPAGATION OF PHONONS IN TOPOLOGICAL SUPERCONDUCTORS INDUCED BY STRAIN FIELDS INSTANTONS

We show that for a multiple-connected space the low energy strain fields excitations are given by instantons, which are controlled by the phase of the superconductor. Dirac fermions with a chiral mass and a superconducting pairing field propagates effectively in a multiple-connected space. When the elastic strain field response is probed one finds that it is given by the Pointriagin characteristic. As a result the space–time metric is modified. Applying an external stress field we observe that the phonon path bends in the transverse direction to the initial direction.

DYNAMICAL COUPLING OF ROTATION WITH THE PAIRING FIELD IN HEAVY NUCLEI

The macroscopic–microscopic model with the Lublin–Strasbourg Drop, the Yukawa–folded single-particle potential and a monopole pairing force is used together with the cranking model to describe rotational bands in even–even actinide ( Ra – Cn ) isotopes. The pairing strength is adjusted for every nucleus to reproduce the experimentally known energy of the rotational 2+ state. The average pairing strength obtained in this way is used to predict the rotational states in superheavy No – Cn nuclei. A simple mechanism which takes into account a dynamical coupling of rotation with the pairing field is explained in detail.