Zobrazeno 1 - 10
of 19
pro vyhledávání: '"Tzerefos, Charalampos"'
Autor:
Tzerefos, Charalampos, Papanikolaou, Theodoros, Basilakos, Spyros, Saridakis, Emmanuel N., Mavromatos, Nick E.
Within the context of a Chern-Simons running-vacuum-model (RVM) cosmology, one expects an early-matter dominated (eMD) reheating period after RVM inflation driven by the axion field. Treating thus in this work Chern-Simons RVM cosmology as an effecti
Externí odkaz:
http://arxiv.org/abs/2411.14223
Gravitational waves (GWs) can undoubtedly serve as a messenger from the early Universe acting as well as a novel probe of the underlying gravity theory. In this work, motivated by one-loop vacuum-polarization effects on curved spacetime, we investiga
Externí odkaz:
http://arxiv.org/abs/2408.17259
Autor:
Basilakos, Spyros, Nanopoulos, Dimitri V., Papanikolaou, Theodoros, Saridakis, Emmanuel N., Tzerefos, Charalampos
In light of NANOGrav data we provide for the first time possible observational signatures of Superstring theory. Firstly, we work with inflection-point inflationary potentials naturally realised within Wess-Zumino type no-scale Supergravity, which gi
Externí odkaz:
http://arxiv.org/abs/2409.02936
Autor:
Papanikolaou, Theodoros, Tzerefos, Charalampos, Basilakos, Spyros, Saridakis, Emmanuel N., Mavromatos, Nick E.
Light primordial black holes (PBHs) with masses $M_\mathrm{PBH}<10^9\mathrm{g}$ can interestingly dominate the Universe's energy budget and give rise to early matter-dominated (eMD) eras before Big Bang Nucleosyntesis (BBN). During this eMD era, one
Externí odkaz:
http://arxiv.org/abs/2402.19373
Publikováno v:
Phys.Rev.D 109 (2024), 084010
It is known that the appearance of microscopic objects with distinct topologies and different Euler characteristics, such as instatons and wormholes, at the spacetime-foam level in Euclidean quantum gravity approaches, leads to spacetime topology cha
Externí odkaz:
http://arxiv.org/abs/2312.07486
Autor:
Basilakos, Spyros, Nanopoulos, Dimitri V., Papanikolaou, Theodoros, Saridakis, Emmanuel N., Tzerefos, Charalampos
The no-scale flipped SU(5) superstring framework constitutes a very promising paradigm for physics below the Planck scale providing us with a very rich cosmological phenomenology in accordance with observations. In particular, it can accommodate Star
Externí odkaz:
http://arxiv.org/abs/2309.15820
Autor:
Basilakos, Spyros, Nanopoulos, Dimitri V., Papanikolaou, Theodoros, Saridakis, Emmanuel N., Tzerefos, Charalampos
In this Letter, we derive for the first time a characteristic three-peaked GW signal within the framework of no-scale Supergravity, being the low-energy limit of Superstring theory. We concentrate on the primordial gravitational wave (GW) spectrum in
Externí odkaz:
http://arxiv.org/abs/2307.08601
Primordial black holes (PBHs) forming out of the collapse of enhanced cosmological perturbations provide access to the early Universe through their associated observational signatures. In particular, enhanced cosmological perturbations collapsing to
Externí odkaz:
http://arxiv.org/abs/2303.16695
Publikováno v:
Eur.Phys.J.C 83 (2023)
Primordial black hole (PBH) fluctuations can induce a stochastic gravitational wave background at second order, and since this procedure is sensitive to the underlying gravitational theory it can be used as a novel tool to test general relativity and
Externí odkaz:
http://arxiv.org/abs/2205.06094
Scalar induced gravitational waves from primordial black hole Poisson fluctuations in $f(R)$ gravity
The gravitational potential of a gas of initially randomly distributed primordial black holes (PBH) can induce a stochastic gravitational-wave (GW) background through second-order gravitational effects. This GW background can be abundantly generated
Externí odkaz:
http://arxiv.org/abs/2112.15059