Related papers: The QCD Axion at Finite Density
We show that holographic models of QCD predict the presence of a Chern-Simons coupling between vector and axial-vector mesons at finite baryon density. In the AdS/CFT dictionary, the coefficient of this coupling is proportional to the…
Hidden axions may be coupled to the standard model particles through a kinetic or mass mixing with QCD axion. We study a scenario in which a hidden axion constitutes a part of or the whole of dark matter and decays into photons through the…
If their number density is high enough, clusters of axions can decay to photons via stimulated emission. We study both the special and general relativistic corrections to lasing in such dense axion clusters as they evolve in static…
If QCD axions form a large fraction of the total mass of dark matter, then axion stars could be very abundant in galaxies. As a result, collisions with each other, and with other astrophysical bodies, can occur. We calculate the rate and…
In this work, we study the effect of (anti)kaon condensation on the properties of compact stars that develop hypernuclear cores with and without an admixture of $\Delta$-resonances. We work within the covariant density functional theory…
We discuss the nature of the kaon condensation phase transition. We find several features which, if kaons condense in neutron stars, are not only remarkable, but must surely effect such properties as superfluidity and transport properties,…
The relic density of dark matter in the $\Lambda$CDM model restricts the parameter space for a cosmological axion field, constraining the axion decay constant, the initial amplitude of the axion field and the axion mass. It is shown via…
Dark matter axion condensates may experience stimulated decays into photon pairs. This effect has been often interpreted as a parametric resonance of photons from the axion-photon coupling, leading to an exponential growth of the photon…
The behavior of QCD at high baryon density and low temperature is crucial to understanding the properties of neutron stars and gravitational waves emitted during their mergers. In this paper we study small systems of baryons in periodic…
The talk is an introduction into diquark condensation phenomena which occur in QCD at high energy density. They are driven by instantons and instanton-antiinstanton pairs (or ``molecules''), which generate attraction in some qq channels. A…
The QCD axion may offer a unified origin for the baryon asymmetry and dark matter through axiogenesis. However, in the minimal QCD axion scenario, axiogenesis either underproduces baryons or overproduces dark matter, and the required…
We determine an `empirical' kaon dispersion relation by analysing and fitting recent experimental data on kaon production in heavy-ion collisions. We then investigate its effects on hadronic equation of state at high densities and on…
The cores of neutron stars harbor the highest matter densities known to occur in nature, up to several times the densities in atomic nuclei. Similarly, magnetic field strengths can exceed the strongest fields generated in terrestrial…
We show that the rotation of the QCD axion field, aided by $B-L$ violation from supersymmetric $R$-parity violating couplings, can yield the observed baryon abundance. Strong sphaleron processes transfer the angular momentum of the axion…
Cosmological evolution of axion field in the early universe might be significantly affected by a thermal friction induced by the axion coupling to thermalized hidden sector. We examine the effects of such a thermal friction on axion dark…
Axion-like particles, including the QCD axion, are well-motivated dark matter candidates. Numerical simulations have revealed coherent soliton configurations, also known as boson stars, in the centers of axion halos. We study evolution of…
The different phases of QCD at finite temperature and density lead to interesting effects in cosmology and astrophysics. In this work I review some aspects of the cosmological QCD transition and of astrophysics at high baryon density.
Recent observations of several massive pulsars, with masses near and above $2~M_\odot$, point towards the existence of matter at very high densities, compared to normal matter that we are familiar with in our terrestrial world. This leads…
An effective Lagrangian for the interaction between a pseudo-scalar (axion-like) field and massive fermions is considered. At high density and non-zero temperature axions can be produced through bremsstrahlung. If the axion-neutron…
As a cold dark matter candidate, the QCD axion may form Bose-Einstein condensates, called axion stars, with masses around $10^{-11}\,M_{\odot}$. In this paper, we point out that a brand new astrophysical object, a Hydrogen Axion Star (HAS),…