Related papers: The Supercooled Universe
Nearly conformal dynamics at the TeV scale as motivated by the hierarchy problem can be characterized by a stage of significant supercooling at the electroweak epoch. This has important cosmological consequences. In particular, a common…
In dimension-less theories of dynamical generation of the weak scale, the Universe can undergo a period of low-scale inflation during which all particles are massless and super-cool. This leads to a new mechanism of generation of the…
We propose a novel gravitational wave production mechanism in the context of quasi-conformal Standard Model extensions, which provide a way to dynamically generate the electroweak scale. In these models, the cosmic thermal history is…
Classically conformal Standard Model extensions predict an intriguing thermal history of the early universe. In contrast to the common paradigm, the onset of the electroweak phase transition can be significantly delayed while the universe…
Cosmological evolution of axion field in the early universe might be significantly affected by a thermal friction induced by the axion coupling to thermalized hidden sector. We examine the effects of such a thermal friction on axion dark…
The quark-hadron phase transition in the early universe can produce inhomogeneities in the distribution of nucleons, which in turn affect the primordial nucleosynthesis. In all the investigations of this problem it has been assumed that the…
The QCD axion is a well-motivated hypothetical particle beyond the Standard Model (SM) and a compelling dark matter candidate. Its relic abundance is highly sensitive to the thermal history of the universe when the temperature is around the…
We examine in the context of supersymmetric models whether the usual cosmological upper bound on the axion decay constant can be relaxed by assuming a period of stronger QCD in the early universe. By evaluating the axion potential in the…
We reanalyze the conditions under which we have a primordial thermal population of axions. Compared with previous studies, we find other processes, involving gluons and quarks, that dominate at high temperatures. We conclude that if the…
If the strong coupling is promoted to a dynamical field-dependent quantity, it is possible that the strong force looked very different in the early Universe. We consider a scenario in which the dynamics is such that QCD confines at high…
Standard lore states that there is tension between the need to accommodate the relic density of a weakly interacting massive particle and direct searches for dark matter. However, the estimation of the relic density rests on an…
The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are…
An interesting feature of a cosmological phase transition can be a stage of exponential expansion (supercooling). The modified expansion history and the entropy injection at reheating, can affect the final energy fraction of dark matter. In…
It is quite possible that the reheat temperature of the universe is extremely low close to the scale of Big Bang nucleosynthesis, i.e. $T_{R}\sim 1-10$ MeV. At such low reheat temperatures generating matter anti-matter asymmetry and…
We investigate the possibility that the Peccei-Quinn phase transition occurs at a temperature far below the symmetry breaking scale. Low phase transition temperatures are typical in supersymmetric theories, where symmetry breaking fields…
We find that QCD can create the cosmological matter abundance via out-of-equilibrium processes during the QCD phase transition, that is what we call the QCD preheating, where the dynamic transition of the QCD vacuum characterized by the…
We discuss production of QCD axion dark matter in a novel scenario, which assumes time-varying scale of Peccei-Quinn symmetry breaking. The latter decreases as the Universe's temperature at early times and eventually stabilises at a large…
Dark Matter could be a composite state of a confining sector with an approximate scale symmetry. We consider the case where the associated pseudo-Goldstone boson, the dilaton, mediates its interactions with the Standard Model. When the…
We consider the production of axion dark matter through the misalignment mechanism in the context of a nonstandard cosmological history involving early matter domination by a scalar field with a time-dependent decay rate. In cases where the…
We suggest that the current acceleration of the universe may be explained by the vacuum energy of a hidden sector which is stuck in a state of equilibrium between phases. The phases are associated to a late-time first-order phase…