### Conveners

#### Nuclear and Astroparticle Physics: F1a

- Andreas Schmitt (University of Southampton)

#### Nuclear and Astroparticle Physics: F1b

- David Blaschke (University of Wroclaw)

#### Nuclear and Astroparticle Physics: F3a

- Thomas Cohen (University of Maryland)

#### Nuclear and Astroparticle Physics: F5a

- Thomas Cohen (University of Maryland)

#### Nuclear and Astroparticle Physics: F5b

- Johann Marton ()

The equation of state (EoS) of nuclear matter is one of the key issues in understanding the physical

properties of neutron stars (NS). Currently, the strongest constraint comes from the fact that the maximum mass for NSs must be larger than about 2Mo, whereas the determination of the radius is still suffering of observational uncertainties and models dependence.

Gravitational wave (GW)...

I will discuss how the process of merger of two compact stars is described within the two-families scenario. In that scenario hadronic stars made of nucleons, of delta resonances and of hyperons can co-exist with strange quark stars made (almost) entirely of deconfined quarks. I will discuss the event of August 2017 at the light of that scheme, concluding that it was associated with the merger...

We discuss the case that GW170817 may not have been the merger of a neutron star (NS) with another neutron star, but rather with a hybrid star (HS) possessing a quark matter core, or even a HS-HS merger, and the implications for the equation of state of dense matter at supersaturation densities.

References:

[1] D. Blaschke & N. Chamel, "Phases of dense matter in compact stars", Chapter 7 of...

The spectacular first detection of gravitational waves from the inspiral and merger of a neutron star binary heralded a new era for relativistic astrophysics. This first event - GW170817 - provided interesting constraints on the neutron star radius (through the inferred tidal deformability) and the supranuclear equation of state. In this talk I will present an overview of these results. I will...

Observations of gravitational waves from neutron star mergers open up novel directions for exploring fundamental physics: they offer the first direct access to the structure of objects with a non-negligible contribution from vacuum energy to their total mass. The presence of such vacuum energy in the inner cores of neutron stars is a natural consequence of possible new QCD phases at large...

Upcoming sky surveys require large-volume, high-quality simulated extra-galactic catalogs for such diverse tasks as investigating various data-analysis strategies, understanding and mitigating systematic errors, developing and testing analysis pipelines, and studying observing strategies. In order to prepare adequately for the rich and complex datasets to be delivered by these surveys, the...

Neutron star mergers provide a great opportunity to gather multi-messenger observational information about nuclear matter at high density and moderate temperature. Numerical simulations of mergers are an essential tool for exploiting this opportunity. However, up to now such simulations have generally not included the effects of transport or dissipation, and have focused on measuring the...

I consider the thermal conductivity and shear viscosity of leptons (electrons and muons) in the nucleon NS cores where protons are in the superconducting state. Charged lepton collision frequencies are mainly determined by the transverse plasmon exchange and are mediated by the character of the transverse plasma screening. In superconducting neutron star core protons give the dominant...

Refined calculations of transport phenomena are likely to be in demand in the emerging era of multi-messenger neutron star observations. The outer core of neutron stars presumably consists of a dense plasma comprised of degenerate electrons, muons, protons, and neutrons. Transport phenomena in this region are of particular phenomenological relevance as they impact the damping of hydrodynamic...

The appearance of strangeness in compact stars is uncertain in both, the nuclear and quark matter sector. While hyperons are sensitive to coupling constants, the threshold for the appearance of strange quark matter depends on both, coupling constants in the entire light quark sector and the way one models the deconfinement phase transition.

I will present how this can lead to ambiguities which...

We propose a new view of crossover between nuclear and quark matter. There are already some theoretical discussions on a percolation picture to describe how quark degrees of freedom would appear. In such a picture of classical percolation, however, it was overlooked that nuclear interactions also contribute to quark mobility, and the physical mechanism to make quark wave-functions localized...

In most studies of the QCD phase structure at nonzero temperature and density it is assumed that the chiral condensate is constant in space. Allowing for spatially modulated condensates on the other hand, it was found in various model calculations that in certain regions of the phase diagram such inhomogeneous condensates are favored over homogeneous ones. For instance it was shown that in a...

It is generally believed that systems with two fermion species that form Cooper pairs form a neutral state, where the number densities of the two fermion species are equal. This belief is based on mean field calculations with a zero-range contact interaction. We have put this claim to the test using a Yukawa model, where the interaction range is finite. The results of this study suggest that...

We discuss the fixed-point structure and symmetry breaking patterns of hot and dense QCD. Our study particularly addresses the phase structure at low temperature and large quark chemical potential, a region where the application of fully first-principles approaches is currently difficult at best. To this end, we employ a Fierz-complete set of four-quark interactions which are dynamically...

In this talk I will discuss various aspects of pion condensation at finite

temperature and density. At T=0, the phase diagram will be mapped

out in the mu_I-mu_B plane, and we

will discuss the competition between an inhomogeneous chiral condensate and

a pion condensate. At finite T, we map out the phase diagram in the

mu_I-T plane focusing on the deconfinement and chiral transitions as...

The ground state of QCD in sufficiently strong magnetic fields and at nonzero baryon chemical potential is a topological crystal made of neutral pions: the Chiral Soliton Lattice (CSL). Due to its topological nature, it carries nonzero baryon number density that can reach values relevant for the cores of neutron stars. The spectrum of excitations above the CSL ground state contains a soft,...

Recent lattice QCD studies at vanishing density exhibit the parity-doubling structure for the low-lying baryons around the chiral crossover temperature. This finding is likely an imprint of the chiral symmetry restoration in the baryonic sector of QCD, and is expected to occur also in cold dense matter, which makes it of major relevance for compact stars. By contrast, typical effective models...

In color-superconducting quark matter gluons and photons mix, and thus an external ordinary magnetic field may induce color-magnetic flux tubes. I will discuss the structure of these flux tubes, in particular pointing out a novel flux tube configuration in color-flavor locked quark matter that has a 2SC core, rather than a completely unpaired one. This configuration is energetically preferred...

The so-called chiral soliton lattice was recently found to describe the ground state of the dense QCD matter in strong magnetic fields. Such a state consists of a periodic array of topological solitons, spontaneously breaks the parity and the translational symmetry and is known to appear also in condensed-matter systems such as chiral magnets. Motivated by the fact that the QCD-like theories...

The behavior of the $\phi$ meson in nuclear matter has attracted renewed interest because of (recent and future) experiments that aim to study the $\phi$ meson properties in nuclei [1-3]. Theoretically, many works have however been conducted for the $\phi$ meson at rest with respect to the nuclear medium [4-5]. In this presentation, I will review recent theoretical progress about the behavior...

The study of the antikaon nucleon system at very low energies plays a key

role in the study of the strong interaction with strangeness, with important

impact in particle and nuclear physics and astrophysics. Exotic atoms

measurements, in particular kaonic hydrogen and deuterium, allow to

determine the s-wave antikaon-nucleon ispospin dependent scattering lengths.

Taking advantage of the...

Anchoring the nuclear interaction in QCD is a long-outstanding problem in nuclear physics. While the lattice community has made enormous progress in mesonic physics and single nucleon physics, continuum-limit physical-point multi-nucleon physics has remained out of reach. I will review CalLat's strategy for multi-nucleon spectroscopy and our latest results.

A nonzero electric dipole moment (EDM) of the neutron, proton, deuteron or helion, in fact, of any finite system necessarily involves the breaking of a symmetry, either by the presence of external fields (i.e., electric fields leading to the case of induced EDMs) or explicitly by the breaking of the discrete parity and time-reflection symmetries in the case of permanent EDMs. Recent results...

On account of symmetry energy dropping with density, nuclear isovector density extends farther out than the isoscalar density, leading to an isovector aura surrounding a nucleus. The faster the drop of the symmetry energy and energy of neutron matter with density, the thicker the aura. The width and sharpness of the aura can be assessed by simultaneously analyzing elastic scattering and...