44 citations · 97 across the 5 of their papers we have counts for
5 papers
Superradiance Effect of a Black Hole Immersed in an Expanding Universe
Stella Kiorpelidi, Konstantinos Ntrekis, Eleftherios Papantonopoulos
We studied the superradiance effect of a charge black hole immersed in an expanding Universe. We considered a test massive charged scalar field scattered off the horizon of the cha…
Unification of Dark Matter - Dark Energy in Generalized Galileon Theories
George Koutsoumbas, Konstantinos Ntrekis, Eleftherios Papantonopoulos +1
We present a unified description of the dark matter and the dark energy sectors, in the framework of shift-symmetric generalized Galileon theories. Considering a particular combina…
Gravitational Collapse of a Homogeneous Scalar Field Coupled Kinematically to Einstein Tensor
George Koutsoumbas, Konstantinos Ntrekis, Eleftherios Papantonopoulos +1
We study the gravitational collapse of a homogeneous time-dependent scalar field that, besides its coupling to curvature, it is also kinematically coupled to the Einstein tensor. T…
Quantum phase transition of high dimensional Yang-Mills theories
Nikos Irges, George Koutsoumbas, Konstantinos Ntrekis
We determine the critical value of the coupling where the first order quantum phase transition takes place for lattice SU(2) Yang-Mills theories in dimensions higher than four. Wit…
Gravitational Particle Production in Gravity Theories with Non-minimal Derivative Couplings
George Koutsoumbas, Konstantinos Ntrekis, Eleftherios Papantonopoulos
We study the gravitational production of heavy X-particles of mass of the order of the inflaton mass, produced after the end of inflation. We find that, in the presence of a deriva…