47 citations · 257 across the 17 of their papers we have counts for
17 papers
Axion Inflation: Perturbative control in the strong backreaction regime
Valerie Domcke, Alexandros Papageorgiou, Marco Peloso +1
We study the strong backreaction regime in axion inflation, in which the friction from Abelian gauge fields generated via the pseudo-scalar interaction $\fracβ{4 M_p} ϕF {\tilde F}…
Scale-dependent chirality as a smoking gun for Abelian gauge fields during inflation
Ogan Özsoy, Alexandros Papageorgiou, Matteo Fasiello
Axion-inflation models are a compelling candidate as a mechanism behind the accelerated expansion in the early universe in light of the possibility to embed them in higher dimensio…
A novel PBH production mechanism from non-Abelian gauge fields during inflation
Ema Dimastrogiovanni, Matteo Fasiello, Alexandros Papageorgiou
We consider the case of axion-like particles (ALPs) during inflation. When coupled to a non-Abelian gauge sector via a Chern-Simons term, ALPs support an intriguing, testable, phen…
Axion-Gauge Dynamics During Inflation as the Origin of Pulsar Timing Array Signals and Primordial Black Holes
Caner Unal, Alexandros Papageorgiou, Ippei Obata
We demonstrate that the recently announced signal for a stochastic gravitational wave background (SGWB) from pulsar timing array (PTA) observations, if attributed to new physics, i…
Dissipative Emergence of Inflation from Quasi-Cyclic Universe
Hiroki Matsui, Alexandros Papageorgiou, Fuminobu Takahashi +1
Inflationary models, especially those with plateau-type potentials, are consistent with the cosmological data, but inflation itself does not resolve the initial singularity. This s…
Dissipative Genesis of the Inflationary Universe
Hiroki Matsui, Alexandros Papageorgiou, Fuminobu Takahashi +1
We study an inflation model with a flat scalar potential supported by observations and find that slow-roll inflation can emerge after a quasi-cyclic phase of the Universe, where it…
A flashing beacon in axion inflation: recurring bursts of gravitational waves in the strong backreaction regime
Juan Garcia-Bellido, Alexandros Papageorgiou, Marco Peloso +1
The coupling between a pseudo-scalar inflaton and a gauge field leads to an amount of additional density perturbations and gravitational waves (GWs) that is strongly sensitive to t…
Constraining modified gravity theories with scalar fields using black-hole images
Georgios Antoniou, Alexandros Papageorgiou, Panagiota Kanti
We study a number of well-motivated theories of modified gravity with the common overarching theme that they predict the existence of compact objects such as black holes and wormho…
Axion dark matter from frictional misalignment
Alexandros Papageorgiou, Pablo Quílez, Kai Schmitz
We study the impact of sphaleron-induced thermal friction on the axion dark-matter abundance due to the interaction of an axion-like particle (ALP) with a dark non-abelian gauge se…
Rectifying No-Hair Theorems in Gauss-Bonnet theory
Alexandros Papageorgiou, Chan Park, Miok Park
We revisit the no-hair theorems in Einstein-Scalar-Gauss-Bonnet theory with a general coupling function between the scalar and the Gauss-Bonnet term in four dimensional spacetime.…
Gravitational Wave Signatures from Warm Dark Energy
Alexandros Papageorgiou
Motivated by some of the recent swampland conjectures, we study a model of dark energy, in which a quintessence axion slowly rolls in a steep potential due to its interactions with…
Warm dark energy
Gianguido Dall'Agata, Sergio Gonzalez-Martin, Alexandros Papageorgiou +1
Motivated by some of the recent swampland conjectures, we study the implementation for the late time acceleration of the Universe of a mechanism developed by Anber and Sorbo in the…
Nonlinear perturbations from axion-gauge fields dynamics during inflation
Alexandros Papageorgiou, Marco Peloso, Caner Unal
We study a variant of the Chromo-Natural Inflation (CNI) mechanism in which the inflaton interacts only gravitationally with the CNI fields. Integrating out all the non-dynamical s…
Nonlinear perturbations from the coupling of the inflaton to a non-Abelian gauge field, with a focus on Chromo-Natural Inflation
Alexandros Papageorgiou, Marco Peloso, Caner Unal
Several models of inflation employing a triplet of SU(2) vectors with spatially orthogonal vacuum expectation values (VEVs) have been recently proposed. One (tensor) combination $t…
Comparison of the linear bias models in the light of the Dark Energy Survey
Alexandros Papageorgiou, Spyros Basilakos, Manolis Plionis
The evolution of the linear and scale independent bias, based on the most popular dark matter bias models within the CDM cosmology, is confronted to that of the Dark Energy Surv…
Gravitational leptogenesis in Natural Inflation
Alexandros Papageorgiou, Marco Peloso
We compute the gravitational leptogenesis generated from the parity-violating gravitational waves sourced by an abelian gauge field coupled to a pseudo-scalar inflation. We show th…
A Consistent Comparison of Bias Models using Observational Data
A. Papageorgiou, M. Plionis, S. Basilakos +1
We investigate five different models for the dark matter halo bias, ie., the ratio of the fluctuations of mass tracers to those of the underlying mass, by comparing their cosmologi…