相关论文: Waterfall stiff period can generate observable pri…
I will review briefly how inflation is expected to generate a stochastic background of primordial gravitational waves (GWs). Then, I will discuss how such GWs can be enhanced by a stiff period following inflation, enough to be observable. I…
Cosmic inflation is the leading theory to explain early Universe history and structure formation. Non-oscillatory inflation is a class of models which can naturally introduce a post-inflationary stiff period of the Universe's evolution…
We explore the cosmological and astrophysical implications of a realistic hybrid inflation model based on flipped $SU(5)$. The model contains superheavy metastable cosmic strings arising from a waterfall field that encounters a limited…
We consider true vacuum bubbles generated in a first order phase transition occurring during the slow rolling era of a two field inflation: it is known that gravitational waves are produced by the collision of such bubbles. We find that the…
We show that a hybrid inflation model with multiple waterfall fields can result in the formation of primordial black hole (PBH) with an astrophysical size, by using an advanced algorithm to follow the stochastic dynamics of the waterfall…
We revisit the hybrid inflation model within the framework of the Grand Unified Theory (GUT), focusing on cases where the waterfall phase transition extends over several e-foldings to dilute monopoles. Considering the stochastic effects of…
First order phase transitions in the early universe can give rise to a stochastic background of gravitational waves. A hypothetical first order electroweak phase transition is particularly interesting in this respect, since the signal is in…
We study the onset of vector instabilities in the post-inflationary epoch of the Universe as a mechanism for primordial magnetic fields amplification. We assume the presence of a charged spectator scalar field arbitrarily coupled to gravity…
The decay of massive particles during inflation generates characteristic signals in the squeezed limit of the primordial bispectrum. These signals are in particular distinctive in the regime of the quasi-single field inflation, where…
We explore a class of realistic supersymmetric hybrid inflation models with a predicted scalar spectral index $n_s \approx 0.97-0.978$, which is in good agreement with the recent Atacama Cosmology Telescope (ACT) measurement. The waterfall…
Within a recently proposed classically conformal model, in which the generation of neutrino masses is linked to spontaneous scale symmetry breaking, we investigate the associated phase transition and find it to be of strong first order with…
We construct a hybrid-inflation model where the inflaton potential is generated radiatively, as gauge symmetries guarantee it to be accidentally flat at tree level. The model can be regarded as a small-field version of Natural Inflation,…
The reheating of the universe after hybrid inflation proceeds through the nucleation and subsequent collision of large concentrations of energy density in the form of bubble-like structures moving at relativistic speeds. This generates a…
The reheating of the universe after hybrid inflation proceeds through the nucleation and subsequent collision of large concentrations of energy density in the form of bubble-like structures moving at relativistic speeds. This generates a…
The nonlinear coupling between spacetime geometry and matter in the early Universe remains a frontier in theoretical cosmology. By introducing a novel gravitomagnetic-hydrodynamic framework, we reveal a fundamental analogy between…
We investigate two classes of inflationary models, which lead to a stiff period after inflation that boosts the signal of primordial gravitational waves (GWs). In both families of models studied, we consider an oscillating scalar…
A stochastic background of gravitational waves can be generated during a cosmological first order phase transition, at least by two distinct mechanisms: collisions of true vacuum bubbles and turbulence in the cosmic fluid. I compare these…
We discuss the waterfall that ends hybrid inflation. Making some simplifying assumptions, that may be satisfied by GUT inflation models, two issues are addressed. First, the procedure of keeping the quantum fluctuation of the waterfall…
We study the production, spectrum and detectability of gravitational waves in models of the early Universe where first order phase transitions occur during inflation. We consider all relevant sources. The self-consistency of the scenario…
It is widely believed that the standard model is a low energy effective theory which may have higher dimensional non-renormalizable operators. The existence of these new operators can lead to interesting dynamics for the evolution of the…