139 citations · 1.4k across the 29 of their papers we have counts for
32 papers
Where is the conformal coupling in Palatini gravity?
Alexandros Karam, Sotirios Karamitsos
We study the conformal coupling in the torsion-free Palatini formulation with an ordinary scalar kinetic term. Tuning the curvature coupling cannot restore Weyl invariance in a Pal…
Post-Newtonian Constraints on Scalar-Tensor Gravity
Alexandros Karam, Samuel Sánchez López, José Jaime Terente Díaz
Solar-System constraints on a general scalar-tensor theory with generic non-minimal coupling function, non-canonical kinetic function, and scalar potential, are investigated in bot…
Has ACT measured radiative corrections to the tree-level Higgs-like inflation?
Ioannis D. Gialamas, Alexandros Karam, Antonio Racioppi +1
Starobinsky inflation and nonminimally coupled (NMC) Higgs inflation have been among the most favored models of the early Universe, as their predictions for the scalar spectral ind…
How deep is the dip and how tall are the wiggles in inflationary power spectra?
Vadim Briaud, Alexandros Karam, Niko Koivunen +3
We study linear scalar perturbations in single-field models of inflation featuring a non-attractor phase. These models lead to a peak in the curvature power spectrum that may resul…
Observable Gravitational Waves from Hyperkination in Palatini Gravity and Beyond
Samuel Sánchez López, Konstantinos Dimopoulos, Alexandros Karam +1
We consider cosmology with an inflaton scalar field with an additional quartic kinetic term. Such a theory can be motivated by Palatini modified gravity. Assuming a runaway…
Scale-Invariant Model for Gravitational Waves and Dark Matter
Alexandros Karam, Maciej Kierkla, Bogumiła Świeżewska
We have conducted a revised analysis of the first-order phase transition that is associated with symmetry breaking in a classically scale-invariant model that has been extended wit…