相关论文: Understanding gravitational particle production in…
In previous work we argued that the correct procedure to predict the gravitational wave signal from preheating after inflation rests on the in-in formalism. We extend here our previous analysis to include the backreaction of the produced…
We study the production of gravitinos during the preheating era after inflation by means of the non-perturbative Bogolyubov technique. Considering only the helicity $\pm 3/2$ states, the problem is reduced to the simpler Dirac fermions…
Cosmic Microwave Background (CMB) observations are used to constrain reheating to Standard Model (SM) particles after a period of inflation. As a light spectator field, the SM Higgs boson acquires large field values from its quantum…
The warm inflation paradigm considers the continuous production of radiation during inflation due to dissipative effects. In its strong dissipation limit, warm inflation gives way to a radiation dominated Universe. High scale inflation then…
We show that a quadratic $U(1)$-breaking term, together with an effective chemical potential induced by a dimension five derivative coupling between the inflaton and the $U(1)$ current, can drive efficient particle production during…
There are two processes of matter creation after inflation that may be relevant to the resolution of the puzzle of cosmic rays observed with energies beyond GZK cut-off: 1) gravitational creation of superheavy (quasi)stable particles, and…
In this work, we explore primordial black holes (PBH) formation scenario during the post-inflationary preheating stage dominated by the inflaton field. We consider, in particular, a model-independent parametrization of the Gaussian peak…
I review two mechanisms by which gravitational waves can be generated at the end of inflation: preheating, and gravitons Hawking radiated during the decay of very small primordial black holes. These mechanisms are contrasted with the…
We consider gravitational particle production (GPP) of dark matter (DM) under a supergravity framework, where the $\alpha$-attractor inflation model is used. The particle spectrum is computed numerically and the DM number density is…
A large class of quintessential inflationary models, recently proposed by Peebles and Vilenkin, leads to post-inflationary phases whose effective equation of state is stiffer than radiation. The expected gravitational waves logarithmic…
In this paper, we consider a model of quintessential inflation based upon inverse hyperbolic potential. We employ curvaton mechanism for reheating which is more efficient than gravitational particle production; the mechanism complies with…
Gravitational production of massive particles due to cosmic expansion can be significant during the inflationary and reheating period of the Universe. If the particle also has non-gravitational interactions that do not significantly affect…
We propose a scenario for inflation based upon the braneworld picture, in which high-energy corrections to the Friedmann equation permit inflation to take place with potentials ordinarily too steep to sustain it. Inflation ends when the…
We consider the conditions for the decay products of perturbative inflaton decay to thermalize. The importance of considering the full spectrum of inflaton decay products in the thermalization process is emphasized. It is shown that the…
We propose a novel mechanism where a first-order phase transition modulates the decay rate of a massive field. This modulation, even if the scalar field has negligible energy density, subsequently generates an observable stochastic…
We study the effects of the unstable gravitino on the big-bang nucleosynthesis. If the gravitino mass is smaller than \sim 10 TeV, primordial gravitinos produced after the inflation are likely to decay after the big-bang nucleosynthesis…
We develop a new approach to gravitational waves in which the Einstein equations are governed by the cosmological constant which is related to the existence of a manifold which is closed. We study an example in which the matter Lagrangian…
We consider the framework of quintessential inflation in the warm background which is caused by the dissipation of the scalar field energy density into relativistic degrees of freedom. The dissipation process has important consequences for…
We consider the production of gravitational KK modes via cosmological photon-photon and electron-positron annihilation in models with large factorisable extra dimensions. We place constraints on this production using recent results from a…
A variety of mechanisms in the early Universe lead to the generation of gravitational waves (GWs). We introduce here a novel source of GWs generated by vacuum fluctuations after inflation. Given that gravitons are minimally coupled…