Presentation materials
We study freeze-in production of dark matter (DM) at temperatures far below the dark matter mass. The temperature of the Standard Model (SM) thermal bath may have never been high such that dark matter production via thermal emission has been Boltzmann suppressed. This allows for a significant coupling between the SM and DM, which is being probed by the direct DM detection experiments and...
Direct detection of light dark matter can be significantly enhanced by up-scattering of dark matter with energetic particles in the cosmic ambient. This boosted dark matter flux can reach kinetic energies up to tens of MeV, while the typical kinetic energies of GeV mass dark matter particles in the Milky Way halo are of the order of keV. Dark matter boosted by energetic diffuse supernova...
In the phenomenon of black hole superradiance a rotating black hole loses its angular momentum to a growing cloud of particles. It has been successfully used to place limits on ultralight particles, such as axions and dark photons, with masses
First-order phase transitions at the electroweak scale are predicted by many Standard Model extensions. They could create a stochastic gravitational wave background observable in the millihertz range today. The next-generation spaceborne observatory LISA has the potential of observing these backgrounds. However, possible phase transition signals will be buried under instrument noises and a...
The frequency range of gravitational waves from first-order cosmological phase transitions will be investigated by the upcoming space-based gravitational wave observatory LISA. If we see a signal of cosmological origin, we need to be able to deduce the parameters of the phase transition from the gravitational wave signal to understand the physics behind it. This requires simulations of the...
An oscillating curvature of the spacetime can drive the production of dark matter during reheating, and accurately quantifying this requires the use of both non-perturbative and non-equilibrium methods. In our work, we compare the particle production on a non-minimally coupled scalar field when computed using a classical lattice approach to previous work utilizing Hartree-level 2PI-methods....
Palatini F(R,X) gravity, with X the inflaton kinetic term, proved to be a powerful framework for generating asymptotically flat inflaton potentials. Here we show that the general form of the F(R,X) potential also provides a tail that generates, in principle, quintessential behavior for dark energy. We describe a few examples that fit the observed value of the cosmological constant and discuss...
In this talk I will discuss a recently studied extension of the
natural inflation model comprising a non -
Abelian gauge sector coupled to the axion -
inflaton kinetic term . I will show how such non -
minimal coupling serves as a source of friction for the rolling
inflaton granting at least sixty e -
folds of accelerated expansion for sub -
Planckian values of the axion...
Magnetic monopoles are a common prediction of early universe phase transitions. In particular, any type of a grand unified theory phase transition will produce magnetic monopoles, and it is thought that these monopoles would come to dominate the energy density of the universe. This consitutes the 'monopole problem' of grand unification, which theories of inflation solve by diluting the energy...
Future space-based interferometers offer an unprecedented opportunity to detect signals from the stochastic gravitational wave background originating from a first-order phase transition at the electroweak scale. The phase transition is accompanied by a change of the equation of state from that of pure radiation. In this work we study the effect of this change on the power spectrum of...
The stress energy tensor we all know is related to the existence of a metric. But the metric is not the only character we can take into account when studying a theory of gravity. We can also consider an independent connection. If we do so we will have the hypermomentum tensor in the game too. This can be related to quantities such as torsion and non metricity. What is the role of these...
Lorentz gauge theory of gravity with spontaneous symmetry breaking field provides successful description of ΛCDM model, as well as generalised black hole solutions compared to those in General Relativity. This talk summarises these extensions provided by such theory and explores whether this can be realised with different symmetry group, Euclidean gauge for example, and how this will affect...
