I'll review the current state of affairs in Cosmology. Data from Planck and from Stage III spectroscopic and photometric experiments have firmly established the flat $\Lambda$CDM as the standard cosmological model. Many parameters are now measured with the percent level precision. Nevertheless, some tensions remain, the strongest being the Hubble parameter tension between expansion rate of the...
The early Universe is usually assumed to be thermalised, homogeneous and isotropic, with only small fluctuations. However many new physics scenarios violate these assumptions: Phase transitions or displaced scalar fields lead to large deviations from thermal equilibrium, while topological defects like strings and domain walls represent large anisotropies. This talk will give an overview of...
I will show how first order phase transitions (PT) in the early universe, with relativistic bubble walls, constitute particle accelerators and colliders. These `bubbletrons' offer novel opportunities of observational access to very high energy scales, in addition to the gravitational waves from the PT. As two examples, I will discuss: i) non-adiabatic production of dark matter which is so fast...
The Tunneling Potential Formalism is an alternative to the Euclidean bounce for calculating tunneling actions, that control the decay of metastable vacua. In this talk I will discuss how this formalism can be extended to study other problems, from bubble-of-nothing decays to ungauged Q-balls and more.
The quantum tunneling in quantum field theory has attracted theoretical and phenomenological interests for a long time. Although it has been nearly established in the absence of gravity, there are subtleties in the presence of gravity. We re-formulated quantum tunneling with the Wheeler-deWitt equation and found that there is a possibility that a system may experience both Euclidean and...
The limitations of symmetry-based solutions to naturalness problems have led to seeking answers from the early universe. In this talk I will give an overview of cosmological solutions to naturalness problems, focusing on models of cosmological relaxation and self-organised localisation.
