Related papers: Removing instability of Polonyi-Starobinsky superg…
We study the conditions of restoring supersymmetry (SUSY) after inflation in the supergravity-based cosmological models with a single chiral superfield and a quartic stabilization term in the K\"ahler potential. Some new, explicit, and…
We introduce an $N=1$ supergravity model based on the gauged shift symmetry of a single chiral multiplet, which can be identified with the string dilaton or a compactification modulus. The model allows for a tunably small and positive value…
We argue that the mass of the inflaton can be much smaller than the Hubble constant in supergravity models in which inflation is driven by D--terms and not F--terms. We investigate a supergravity toy model which leads to hybrid inflation…
Inflation in the early universe can generate the nearly conformal invariant fluctuation that leads to the structures we observe at the present. The simple viable Starobinsky $R^2$ inflation has an approximate global scale symmetry. We study…
We study a model including a real scalar field $\phi$ non-minimally coupled to $F({\cal R})$ gravity, which is conformally equivalent to an Einstein-Hilbert theory, involving two real scalar fields. We consider three special cases of the…
We propose a modification of no-scale supergravity models which incorporates sgoldstino stabilization and supersymmetry (SUSY) breaking with a tunable cosmological constant by introducing a Kahler potential which yields a kinetic pole of…
We formulate within Supergravity a model of induced-gravity inflation, excellently consistent with ACT DR6, inspired by the Palatini gravity. The inflaton belongs in the decomposition of a conjugate pair of Higgs superfields which lead to…
A new supergravity D-term, not associated to gauged R-symmetry, was recently discovered and used to construct new supergravity models. In this paper we use a generalization of the new D-term that we used in previous works, to construct a…
We discuss the possibility to construct supergravity models with a single superfield describing inflation as well as the tiny cosmological constant $V \sim 10^{{-120}}$. One could expect that the simplest way to do it is to study models…
We address an issue what kind of tuning realizes a flat potential for inflaton in supergravity. We restrict ourselves to the case that inflationary dynamics is not affected by separate supersymmetry-breaking effects, and consider examples…
We study the solution to the Polonyi problem where the Polonyi field weighs as $O(10{\rm TeV})$ and decays just before the primordial nucleosynthesis. It is shown that in spite of a large entropy production by the Polonyi field decay, one…
We present a D-term hybrid inflation model, embedded in supergravity with moduli stabilisation. Its novel features allow us to overcome the serious challenges of combining D-term inflation and moduli fields within the same string-motivated…
We will present the way to derive a de Sitter inflationary solution within the so-called Starobinsky-Bel-Robinson gravity. Then, we will show by using the dynamical system method whether the obtained solution is stable or not. According to…
We revisit a polynomial chaotic inflation model in supergravity which we proposed soon after the Planck first data release. Recently some issues have been raised in Ref.[12], concerning the validity of our polynomial chaotic inflation…
We consider an inflection point inflationary model in supergravity with a single chiral superfield and show that the predicted values of the scalar spectral index and tensor-to-scalar ratio are consistent with the Planck 2015 results. In…
We consider stability of spherically symmetric solutions in $f(R)$ gravity model proposed by Starobinsky. We find that the model suffers from a severe fine tuning problem when applied to compact objects like neutron stars. The problem can…
We study three types of the old-minimal higher-derivative supergravity theories extending the $f(R)$ gravity, towards their use for the inflationary model building in supergravity, by using both superfields and their field components. In…
The modified supergravity approach is applied to describe a formation of Primordial Black Holes (PBHs) after Starobinsky inflation. Our approach naturally leads to the two-(scalar)-field attractor-type double inflation, whose first stage is…
We consider quantum corrections to a recently obtained perturbative form of Starobinsky model to extract information about the initial conditions of the universe leading to cosmological inflation. Integrating out graviton modes, we find…
We propose a robust supergravity model of dynamical supersymmetry breaking and gauge mediation, and a natural embedding in non-perturbative string theory with D-branes. A chiral field (and its mirror) charged under "anomalous" U(1)'s acts…