The main mechanism responsible for Axion-Like-Particle (ALP) production in the early
universe is the so-called misalignment mechanism. Three regimes have been investigated …

We examine dark-energy models in which a quintessence or a phantom field, ϕ, rolls near
the vicinity of a local minimum or maximum, respectively, of its potential V (ϕ). Under the …

Oscillons are bound states sustained by self-interactions that appear in rather generic scalar
models. They can be extremely long-lived and have a built-in formation mechanism …

Coherent oscillations of a scalar field can mimic the behavior of a perfect fluid with an
equation-of-state parameter determined by the properties of the potential, possibly driving …

A bstract A long-lived scalar field (Φ) which couples weakly to the right-handed (RH)
neutrinos (N Ri), generates small RH neutrino masses (M i) in Low-Scale-Leptogenesis …

A bstract The fact that fast oscillating homogeneous scalar fields behave as perfect fluids in
average and their intrinsic isotropy have made these models very fruitful in cosmology. In …

We explore the scalar field obtained under the conformal transformation of the spacetime
metric g μν from the Jordan frame to the Einstein frame in f (R) gravity. This scalar field is the …

Starting from the evidence that dark matter (DM) indeed exists and permeates the entire
cosmos, various bounds on its properties can be estimated. Beginning with the cosmic …

During the last 3 years the pulsar timing arrays reported a series of repeated evidences of
gravitational radiation (with stochastically distributed Fourier amplitudes) at a benchmark …

Oscillating scalar fields, with an oscillation frequency much greater than the expansion rate,
have been proposed as models for dark energy. We examine these models, with particular …