Related papers: Entropy Production in Affine Inflation
The existence of magnetic fields in the universe is unmistakable. They are observed at all scales from stars to galaxy clusters. However, the origin of these fields remains enigmatic. It is believed that magnetic field seeds may have…
We investigate the generation of features at large scales in the primordial power spectrum (PPS) when inflation is driven by two scalar fields. In canonical single field models of inflation, these features are often generated due to…
Inflationary dynamics driven by multiple fields, especially with nonminimal couplings, allow for highly interesting features such as isocurvature, non-Gaussianity, and preheating. In this paper, we study two-field inflation in the context…
We study the generation of the primordial curvature perturbation in multi-field inflation. Considering both the evolution of the perturbation during inflation and the effects generated at the end of inflation, we present a general formula…
We revisit natural inflation within the framework of metric-affine gravity, considering the impact of a periodic non-minimal coupling between the inflaton and the Nieh-Yan term. Such a term, alone, leads to linear inflation predictions in…
We describe new scenarios of generating curvature perturbations when inflaton (curvaton) has significant interactions. We consider a ``spot'', which arises from interactions associated with enhanced symmetric point (ESP) on the trajectory.…
Recently multi-field inflation models that can produce large scalar fluctuations on small scales have drawn a lot of attention, primarily because they could lead to primordial black hole production and generation of large second-order…
We examine the inflationary modes in the cubic curvature theories in the context of asymptotically safe gravity. On the phase space of the Hubble parameter, there exists a critical point which corresponds to the slow-roll inflation in…
Precise measurements of the microwave background anisotropy have confirmed the inflationary picture of approximately scale invariant, Gaussian primordial adiabatic density perturbations. However, there are some anomalies that suggest a…
We show how short inflation naturally arises in a non-minimal gravity theory with a scalar field without any potential terms. This field drives inflation solely by its derivatives, which couple to the matter only through the combination…
In the general framework of Metric-Affine theories of gravity, where the metric and the connection are independent variables, we consider actions quadratic in the Ricci scalar curvature and the Holst invariant (the contraction of the…
When inflation is driven by a pseudo-scalar field \chi coupled to vectors as \alpha/4 \chi F \tilde F, this coupling may lead to a copious production of gauge quanta, which in turns induces non-Gaussian and non-scale invariant corrections…
Non-minimal actions with matter represented by a scalar field coupled to gravity are considered in the context of a homogeneous and isotropic universe. The coupling is of the form $-\xi/2 \phi^2 R$. The possibility of successful inflation…
On compactification from higher dimensions, a single free massive scalar field gives rise to a set of effective four-dimensional scalar fields, each with a different mass. These can cooperate to drive a period of inflation known as assisted…
In this talk we present a mechanism for leptogenesis which is based on gravity waves produced during inflation. We show that when inflation is driven by a pseudo-scalar field the metric perturbations generated during inflation can become…
We study primordial perturbations in Higgs--$R^2$ inflation in the presence of non-minimal kinetic mixing between the Higgs field and the scalaron. By numerically solving the multifield background and linear perturbation equations, we…
The shift-symmetric coupling of a pseudo-scalar particle driving inflation to gauge fields provides a unique way of probing cosmic inflation. We show for an SU(2) gauge group how a classical isotropic background gauge field develops from…
We calculate the primordial spectrum of scalar perturbations of the 3-form inflation and we find that the curvature perturbations decay at late times. As as result, although a non-minimally coupled massive 3-form field may drive inflation…
Any attempt to understand the ubiquitous nature of the magnetic field in the present universe seems to lead us towards its primordial origin. For large-scale magnetic fields, however, their strength and length scale may not necessarily…
In this note we argue that the breaking of conformal invariance because of the coupling of a charged scalar field to gravity is not sufficient for the production of seed galactic magnetic fields during inflation.