I review the dark bubble model, its connection to quantum cosmology and how the cosmological constant can be computed in terms of other fundamental scales.
Palatini F(R) gravity proved to be a powerful tool in order to realize asymptotically flat inflaton potentials. Unfortunately, it also inevitably implies higher-order inflaton kinetic terms in the Einstein frame that might jeopardize the evolution of the system out of the slow-roll regime. We prove that a F(R−X) gravity, where X is the inflaton kinetic term, solves the issue. Moreover, when F...
Primordial black holes are a candidate for dark matter. Their seeds may be generated during inflation. I discuss the mechanism, why stochastic effects are expected to be important, and how they can be modelled consistently. I will also discuss new results on how stochastic fluctuations make the density profiles that collapse into black holes very choppy, unlike assumed so far.
The primordial universe may provide a window to the highest energy densities accessible in nature. The observational detection of primordial non-Gaussianity and/or primordial features would therefore shed unique light on the laws of physics at scales far beyond those of any terrestrial experiment. In this talk, I will show how current and future large-scale structure (LSS) surveys can place...
The epoch of reionisation marks the emergence of the first galaxies that emit light into the intergalactic medium, leading to the ionisation and heating of the Universe. This phase is a forefront area in astrophysics. While our current understanding relies on theoretical models of early galaxy formation within the standard cold dark matter (CDM) cosmology, recent observations, including early...
I explore the possibility of dark matter being composed of stable scalar glueballs from a confining dark SU(N) gauge theory. The relic abundance of these glueballs is studied for the first time in a thermal effective theory, using an effective potential fitted by lattice simulations. The predicted relic abundance is smaller than previously believed. Moreover, this framework can be easily...
Many extensions of the Standard Model of particle physics predict that one or more phase transitions took place in the early universe. Such phase transitions involve the nucleation, expansion, and collision of bubbles of the new phase. These collisions (and associated interactions of sound waves in the plasma) are substantial, potentially detectable, sources of gravitational waves. As a...
The cosmic microwave background (CMB) gives us information about the earliest history of the Universe, close after the Big Bang. After half a century of more and more sensitive CMB observations, from ground, space and balloons, we now have dozens of valuable data sets available. Each of these has their own strengths and weaknesses, including sensitivity, resolution, frequency bands, sky...
Fifth forces are ubiquitous in modified theories of gravity. In this talk, I present our recent results investigating their effect on the Cepheid-calibrated cosmic distance ladder, specifically with respect to the inferred value of the Hubble constant (H0). We consider a variety of effective models where the strength of the fifth force is estimated using proxy fields related to the large-scale...
The standard model of cosmology predicts a rich phenomenology to test the fundamental physics of the origin of cosmic structure, the accelerating cosmic expansion, and dark matter with next-generation galaxy surveys. However, traditional data analysis methods focus on limited statistical summaries and overlook important information in the complex filamentary distribution of cosmic matter in...
Cosmic strings are one-dimensional topological defects expected to form in the early-universe by many extensions of the Standar Model. In the case of axion models, the resulting strings, called global strings, then decay via the emission of particles and gravitational waves. In this talk, I will present a recent work in which we studied the simultaneous decay of isolated global string loops...
Standard approaches taken in theoretical calculations of phase transition quantities, such as the critical temperature or the bubble nucleation rate, suffer from a wide range of ambiguities: gauge dependence, strong renormalization scale dependence, IR divergences, imaginary potentials… Though a daunting list, these problems can be resolved with the proper methods. The issue is that phase...
The discovery of gravitational waves by the LIGO-Virgo collaboration was a watershed moment for fundamental physics. Now, with the hint gravitational waves from pulsar timing arrays, and with the anticipated LISA experiment on the horizon, particle physics, too, turns to studying these waves. Nevertheless, a link between gravitational-waves and fundamental physics can not be formed without...
