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In this work we investigate the thermodynamics conditions at which neutrinos decouple from matter in neutron star merger remnants by post-processing results of merger simulations. We find that the matter density and the neutrino energies are the most relevant quantities in determining the decoupling surface location. For mean energy neutrinos ( ∼ 9, 15 and 24 MeV for ν e , ν ¯ e and ν μ , τ , respectively) the transition between diffusion and free-streaming conditions occurs around 10 11 g cm - 3 for all neutrino species. Weak and thermal equilibrium freeze-out occurs deeper (several 10 12 g cm - 3 ) for heavy-flavor neutrinos than for ν ¯ e and ν e ( ≳ 10 11 g cm - 3 ). Decoupling temperatures are broadly in agreement with the average neutrino energies, with softer equations of state characterized by ∼ 1 MeV larger decoupling temperatures. Neutrinos streaming at infinity with different energies come from different remnant parts. While low-energy neutrinos ( ∼ 3 MeV ) decouple at ρ ∼ 10 13 g cm - 3 , T ∼ 10 MeV and Y e ≲ 0.1 close to weak equilibrium, high-energy ones ( ∼ 50 MeV ) decouple from the disk at ρ ∼ 10 9 g cm - 3 , T ∼ 2 MeV and Y e ≳ 0.25 . The presence of a massive NS or a BH influences the neutrino thermalization. While in the former case decoupling surfaces are present for all relevant energies, the lower maximum density ( ≲ 10 12 g cm - 3 ) in BH-torus systems does not allow softer neutrinos to thermalize and diffuse.

The interpretation of available and forthcoming data obtained from multimessenger astrophysical observations—potentially providing unprecedented access to neutron star properties—will require the development of novel, accurate theoretical models of dense matter. Of great importance, in this context, will be the capability for devising a description of thermal effects applicable to the study of quantities other than the equation of state, such as the transport coefficients and the neutrino mean free path in the nuclear medium. A formalism based on correlated basis states and the cluster expansion technique has been previously employed to derive a well-behaved effective interaction—suitable for use in standard perturbation theory—from a state-of-the-art nuclear Hamiltonian, including phenomenological two- and three-nucleon potentials. Here, we provide a comprehensive and self-contained account of the extension of this approach to the treatment of finite-temperature effects, and report the results of numerical calculations of a number of properties of nuclear matter with arbitrary neutron excess and temperature up to 50 MeV.

The ground-breaking works of Weinberg have opened the way to calculations of atomic nuclei that are based on systematically improvable Hamiltonians. Solving the associated many-body Schrödinger equation involves non-trivial difficulties, due to the non-perturbative nature and strong spin-isospin dependence of nuclear interactions. Artificial neural networks have proven to be able to compactly represent the wave functions of nuclei with up to A=4 nucleons. In this work, we extend this approach to 6Li and 6He nuclei, using as input a leading-order pionless effective field theory Hamiltonian. We successfully benchmark their binding energies, point-nucleon densities, and radii with the highly-accurate hyperspherical harmonics method.

Ultra-cold Fermi gases exhibit a rich array of quantum mechanical properties, including the transition from a fermionic superfluid Bardeen-Cooper-Schrieffer (BCS) state to a bosonic superfluid Bose-Einstein condensate (BEC). While these properties can be precisely probed experimentally, accurately describing them poses significant theoretical challenges due to strong pairing correlations and the non-perturbative nature of particle interactions. In this work, we introduce a Pfaffian-Jastrow neural-network quantum state featuring a message-passing architecture to efficiently capture pairing and backflow correlations. We benchmark our approach on existing Slater-Jastrow frameworks and state-of-the-art diffusion Monte Carlo methods, demonstrating a performance advantage and the scalability of our scheme. We show that transfer learning stabilizes the training process in the presence of strong, short-ranged interactions, and allows for an effective exploration of the BCS-BEC crossover region. Our findings highlight the potential of neural-network quantum states as a promising strategy for investigating ultra-cold Fermi gases. The theoretical description of ultra-cold Fermi gases is challenging due to the presence of strong, short-ranged interactions. This work introduces a Pfaffian-Jastrow neural-network quantum state that outperforms existing Slater-Jastrow frameworks and diffusion Monte Carlo methods.

This review paper emphasizes the significance of microscopic calculations with quantified theoretical error estimates in studying lepton–nucleus interactions and their implications for electron scattering and accelerator neutrino oscillation measurements. We investigate two approaches: Green’s Function Monte Carlo and the extended factorization scheme, utilizing realistic nuclear target spectral functions. In our study, we include relativistic effects in Green’s Function Monte Carlo and validate the inclusive electron scattering cross section on carbon using available data. We compare the flux-folded cross sections for neutrino-carbon scattering with T2K and MINERνA experiments, noting the substantial impact of relativistic effects in reducing the theoretical curve strength when compared to MINERνA data. Additionally, we demonstrate that quantum Monte Carlo-based spectral functions accurately reproduce the quasi-elastic region in electron scattering data and T2K flux-folded cross sections. By comparing results from Green’s Function Monte Carlo and the spectral function approach, which share a similar initial target state description, we quantify errors associated with approximations in the factorization scheme and the relativistic treatment of kinematics in Green’s Function Monte Carlo.

An accurate description of low-density nuclear matter is crucial for explaining the physics of neutron star crusts. In the density range between approximately 0.01 fm −3 and 0.1 fm −3 , matter transitions from neutron-rich nuclei to various higher-density pasta shapes, before ultimately reaching a uniform liquid. In this work, we introduce a variational Monte Carlo method based on a neural Pfaffian-Jastrow quantum state, which allows us to model the transition from the liquid phase to neutron-rich nuclei microscopically. At low densities, nuclear clusters dynamically emerge from the microscopic interactions among protons and neutrons, which we model based on pionless effective field theory. Our variational Monte Carlo approach represents a significant improvement over the state-of-the-art auxiliary-field diffusion Monte Carlo method, which is severely hindered by the fermion-sign problem in this low-density regime and cannot capture the onset of clusters. In addition to computing the energy per particle of symmetric nuclear matter and pure neutron matter, we analyze an intermediate isospin-asymmetry configuration to elucidate the formation of nuclear clusters. We also provide evidence that the presence of such nuclear clusters influences the amount of protons in the crust compared to protons in beta-equilibrated, neutrino-transparent matter. Low-density nuclear matter, found in neutron star crusts, transitions from neutron-rich nuclei to a uniform liquid of neutrons and protons. The authors present a neural network-based variational Monte Carlo method which enables one to model this transition microscopically, revealing how nucleons self-organize into nuclear clusters from microscopic interactions and improving upon existing approaches.

A fully quantitative description of the equilibrium and dynamical properties of hot nuclear matter will be needed for the interpretation of the available and forthcoming astrophysical data, providing information on the post-merger phase of a neutron star coalescence. We discuss the results of a recently developed theoretical model, based on a phenomenological nuclear Hamiltonian including two- and three-nucleon potentials, to study the temperature dependence of average and single-particle properties of nuclear matter relevant to astrophysical applications. The potential of the proposed approach for describing dissipative processes leading to the appearance of bulk viscosity in neutron star matter is also outlined.

Ageing of the global population represents a challenge for national healthcare systems and healthcare professionals, including medico-legal experts, who assess personal damage in an increasing number of older people. Personal damage evaluation in older people is complex, and the scarcity of evidence is hindering the development of formal guidelines on the subject. The main objectives of the first multidisciplinary Consensus Conference on Medico-Legal Assessment of Personal Damage in Older People were to increase knowledge on the subject and establish standard procedures in this field. The conference, organized according to the guidelines issued by the Italian National Institute of Health (ISS), was held in Bologna (Italy) on June 8, 2019 with the support of national scientific societies, professional organizations, and stakeholders. The Scientific Technical Committee prepared 16 questions on 4 thematic areas: (1) differences in injury outcomes in older people compared to younger people and their relevance in personal damage assessment; (2) pre-existing status reconstruction and evaluation; (3) medico-legal examination procedures; (4) multidimensional assessment and scales. The Scientific Secretariat reviewed relevant literature and documents, rated their quality, and summarized evidence. During conference plenary public sessions, 4 pairs of experts reported on each thematic area. After the last session, a multidisciplinary Jury Panel (15 members) drafted the consensus statements. The present report describes Conference methods and results, including a summary of evidence supporting each statement, and areas requiring further investigation. The methodological recommendations issued during the Conference may be useful in several contexts of damage assessment, or to other medico-legal evaluation fields.

The prediction of neutron stars properties is strictly connected to the employed nuclear interactions. The appearance of hyperons in the inner core of the star is strongly dependent on the details of the underlying hypernuclear force. We summarize our recent quantum Monte Carlo results on the development of realistic two- and threebody hyperon-nucleon interactions based on the available experimental data for light- and medium-heavy hypernuclei.

The presence of exotic states of matter in neutron stars (NSs) is currently an open issue in physics. The appearance of muons, kaons, hyperons, and other exotic particles in the inner regions of the NS, favoured by energetic considerations, is considered to be an effective mechanism to soften the equation of state (EoS). In the so-called two-families scenario , the softening of the EoS allows for NSs characterized by very small radii, which become unstable and convert into a quark stars (QSs). In the process of conversion of a NS into a QS material can be ablated by neutrinos from the surface of the star. Not only neutron-rich nuclei, but also more exotic material, such as hypernuclei or deconfined quarks, could be ejected into the atmosphere. In the NS atmosphere, atoms like H, He, and C should exist, and attempts to model the NS thermal emission taking into account their presence, with spectra modified by the extreme magnetic fields, have been done. However, exotic atoms, like muonic hydrogen ( p μ − ) or the so-called Sigmium (Σ + e − ), could also be present during the conversion process or in its immediate aftermath. At present, analytical expressions of the wave functions and eigenvalues for these atoms have been calculated only for H. In this work, we extend the existing solutions and parametrizations to the exotic atoms ( p μ − ) and (Σ + e − ), making some predictions on possible transitions. Their detection in the spectra of NS would provide experimental evidence for the existence of hyperons in the interior of these stars.