Related papers: The First Particles
To constrain the universe before recombination (380000 years after the Big Bang), we mostly rely on the measurements of the primordial abundances that indicate the first insight into the thermal history of the universe. The first production…
We present aspects of a model which attempts to unify the creation of cold dark matter, a CP-violating baryon asymmetry, and also a small, residual vacuum energy density, in the early universe. The model contains a primary scalar (inflaton)…
A kinetic mixing between the axion and the inflaton allows for a production of axion dark matter even if the inflationary Hubble scale is smaller than the zero-temperature axion mass. We analyze the axion dynamics in this recently…
These lecture notes provide a pedagogical introduction to some aspects of the inflationary cosmology, including the background scalar field dynamics, generation of primordial seed perturbations via quantum fluctuations during inflation, and…
We describe a new mechanism of dark matter production in the early Universe, based on the dynamics of a first order phase transition. We assume that dark matter particles acquire mass during the phase transition, making it energetically…
We consider the production of matter and radiation during reheating after inflation, restricting our attention solely to gravitational interactions. Processes considered are the exchange of a graviton, $h_{\mu \nu}$, involved in the…
We study thermalization of the early Universe when the inflaton can decay into the Standard Model (SM) quarks and gluons, using QCD arguments. We describe the possible formation of the thermal plasma of soft gluons and quarks well before…
When light primordial black holes (PBHs) evaporate in the early Universe, they locally reheat the surrounding plasma, creating hot spots with temperatures that can be significantly higher than the average plasma temperature. In this work,…
We investigate the thermalization process of the Universe after inflation to determine the evolution of the effective temperature. The time scale of thermalization is found to be so long that it delays the evolution of the effective…
In currently popular cosmological scenarios -- all variants of the cold dark matter (CDM) cosmogony -- some time beyond a redshift of 15, stars within the numerous small halos that condense with virial temperatures ~1e4 K created the first…
At the end of inflation the universe is frozen in a near zero-entropy state with energy density in a coherent scalar field and must be ``defrosted'' to produce the observed entropy and baryon number. We propose that the baryon asymmetry is…
We present a minimal UV complete framework to embed inflation and dark matter by extending the standard model with a singlet real scalar field (the inflaton) and a singlet fermonic field acting as dark matter. The inflaton features the most…
We explore cosmological magnetogenesis in the post-inflationary universe, when the inflaton oscillates around its potential minimum and the universe is effectively dominated by cold matter. During this epoch prior to reheating, large-scale…
Despite their tremendous successes, modern-day cosmology and particle physics harbor a variety of unresolved mysteries. Two of the biggest are the origin of the baryon asymmetry of the Universe and the existence and nature of dark matter.…
We speculate that the early Universe was inside a primordial black hole. The interior of the the black hole is a dS background and the two spacetimes are separated on the surface of black hole's event horizon. We argue that this picture…
In these notes we present a selection of topics, each section approximately amounting to one lecture. We begin with a brief recapitulation of General Relativity, and the Standard Model of Cosmology. This is followed by lectures on important…
Over the past three years we have determined the basic features of our Universe. It is spatially flat; accelerating; comprised of 1/3 a new form of matter, 2/3 a new form of energy, with some ordinary matter and a dash of massive neutrinos;…
During (re)heating of the universe after inflation, the relativistic decay products of the inflaton field $\phi$ must lose energy and additional particles must be produced to attain a thermalised state at a temperature $T_{\reh}$. We…
We present a unified model where the same scalar field can drive inflation and account for the present dark matter abundance. This scenario is based on the incomplete decay of the inflaton field into right-handed neutrino pairs, which is…
Primordial Black Holes (PBHs) have entered the forefront of theoretical cosmology, due their potential role in phenomena ranging from gravitational waves, to dark matter, to galaxy formation. While producing PBHs from inflationary…