123 citations · 441 across the 9 of their papers we have counts for
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Inflationary phenomenology of quadratic gravity in the Palatini formulation
Angelos Lykkas
The theory of General Relativity was established on a spacetime manifold equipped with a metric tensor, , and the connection on identified…
Extended interactions in the Palatini- inflation
Angelos Lykkas, Kyriakos Tamvakis
The Palatini formulation of the Starobinsky model does not yield a propagating scalaron that can assume the role of the inflaton field as in the conventional metric formulation. In…
Palatini-Higgs inflation with non-minimal derivative coupling
Ioannis D. Gialamas, Alexandros Karam, Angelos Lykkas +1
The predictions of standard Higgs inflation in the framework of the metric formalism yield a tensor-to-scalar ratio which lies well within the expected accuracy of…
Equivalence of inflationary models between the metric and Palatini formulation of scalar-tensor theories
Laur Järv, Alexandros Karam, Aleksander Kozak +3
With a scalar field non-minimally coupled to curvature, the underlying geometry and variational principle of gravity - metric or Palatini - becomes important and makes a difference…
Constant-roll in the Palatini- models
Ignatios Antoniadis, Angelos Lykkas, Kyriakos Tamvakis
We consider models of a scalar field coupled to quadratic gravity in the framework of the Palatini formulation. The resulting Einstein-frame generalized -inflation e…
Single-field inflation in models with an term
Ignatios Antoniadis, Alexandros Karam, Angelos Lykkas +2
We present two cases where the addition of the term to an inflationary model leads to single-field inflation instead of two-field inflation as is usually the case. In both ca…
Rescuing Quartic and Natural Inflation in the Palatini Formalism
I. Antoniadis, A. Karam, A. Lykkas +2
When considered in the Palatini formalism, the Starobinsky model does not provide us with a mechanism for inflation due to the absence of a propagating scalar degree of freedom. By…
Palatini inflation in models with an term
I. Antoniadis, A. Karam, A. Lykkas +1
The Starobinsky model, considered in the framework of the Palatini formalism, in contrast to the metric formulation, does not provide us with a model for inflation, due to the abse…
Frame-invariant approach to higher-dimensional scalar-tensor gravity
Alexandros Karam, Angelos Lykkas, Kyriakos Tamvakis
The recent interest in modified theories of gravity, involving some type of non-minimal coupling to the Ricci scalar, and the calculation of cosmological observables in the Einstei…
Scalar-Tensor Quintessence with a linear potential: Avoiding the Big Crunch cosmic doomsday
A. Lykkas, L. Perivolaropoulos
All quintessence potentials that are either monotonic with negative interval or have a minimum at negative values of the potential, generically predict a future collapse of the sca…