74 citations · 624 across the 44 of their papers we have counts for
44 papers
A note on oscillons: non-negligible metric fluctuations during preheating
Daniel del-Corral, Paolo Gondolo, K. Sravan Kumar +1
The dominant lattice approach to post-inflationary preheating and oscillon formation evolves an inhomogeneous inflaton field on a spatially homogeneous Friedmann-Lemaître-Robertson…
Unitary Quadratic Quantum Gravity in 4D
K. Sravan Kumar, João Marto
In quadratic gravity, with a positive Weyl squared coefficient, the extra spin-2 sector is shown to correspond to a dual inverted harmonic oscillator, instead of a ghost. Using the…
Quantum (quadratic) gravity: replacing the massive tensor ghost with an inverted harmonic oscillator-like instability
K. Sravan Kumar, João Marto
The quadratic theory of gravity is the unique renormalizable theory of quantum gravity in 4 dimensions, as proved by K. S. Stelle in 1977. Over the decades, the theory has been und…
Power-Law Inflation in n-Dimensional Fractional Scalar Field Cosmology: Observational Constraints and Dynamical Analysis
Daniel Oliveira, Seyed Rasouli, Joao Marto +1
Power-law inflation with is conceptually simple and predicts a scalar tilt compatible with CMB data, but in four-dimensional Einstein gravity it…
A new understanding of Einstein-Rosen bridges
Enrique Gaztañaga, K. Sravan Kumar, João Marto
The formulation of quantum field theory in Minkowski spacetime, which emerges from the unification of special relativity and quantum mechanics, is based on treating time as a param…
Tunnelling in Quantum Cosmology: WKB vs SWKB
Duarte Guimarães, João Marto, Paulo Vargas Moniz
This study analyses WKB and Supersymmetric WKB (SWKB) methods in a closed Friedmann-Robertson-Walker (FRW) minisuperspace model to determine whether they yield different results in…
Gravitational Foundations and Exact Solutions in -Dimensional Fractional Cosmology
S. M. M. Rasouli, J. Marto, D. A. V. Oliveira +1
Three theoretically plausible techniques to developing a fractional scalar field cosmological model are pointed in this paper; the time-dependent kernel weighted action being then…
Primordial black holes through preheating instabilities in -attractor models
Daniel del-Corral, Paolo Gondolo, K. Sravan Kumar +1
In this work, we explore the production of primordial black holes (PBHs) within the context of -attractor inflationary models, focusing on the preheating phase following inflati…
Scalar-Induced Gravitational Waves from self-resonant preheating in -attractor models
Daniel del-Corral, Paolo Gondolo, K. Sravan Kumar +1
After the inflationary phase, the universe enters the preheating phase, during which the inflaton field rolls down its potential and oscillates. When the potential significantly de…
Gravitational waves from primordial black hole dominance: The effect of inflaton decay rate
Daniel del-Corral, K. Sravan Kumar, João Marto
In this work, we explore primordial black holes (PBH) formation scenario during the post-inflationary preheating stage dominated by the inflaton field. We consider, in particular,…
Black-hole evaporation for cosmological observers
Thiago de L. Campos, C. Molina, J. A. S. Lima
This work investigates the evaporation of black holes immersed in a de Sitter environment, using the Vaidya-de Sitter spacetime. The role of cosmological observers is highlighted i…
Hawking radiation with pure states
K. Sravan Kumar, João Marto
Hawking's seminal work on black hole radiation highlights a critical issue in our understanding of quantum field theory in curved spacetime (QFTCS), specifically the problem of uni…
Revisiting quantum field theory in Rindler spacetime with superselection rules
K. Sravan Kumar, João Marto
Quantum field theory (QFT) in Rindler spacetime is a gateway to understanding unitarity and information loss paradoxes in curved spacetime. Rindler coordinates map Minkowski spacet…
Revisiting primordial black holes formation from preheating instabilities: the case of Starobinsky inflation
Daniel del-Corral, Paolo Gondolo, K. Sravan Kumar +1
In recent years, the formation of primordial black holes (PBH) in the early universe inflationary cosmology has garnered significant attention. One plausible scenario for primordia…
Phase space noncommutativity, power-law inflation and quantum cosmology
S. M. M. Rasouli, João Marto
Considering an arbitrary dimensional FLRW universe in the framework of a generalized Sáez--Ballester (SB) theory, we establish a noncommutative (NC) cosmological model. We concentr…
Towards a unitary formulation of quantum field theory in curved space-time: the case of Schwarzschild black hole
K. Sravan Kumar, João Marto
We argue that the origin of unitarity violation and information loss paradox in our understanding of black holes (BH) lies in the standard way of doing quantum field theory in curv…
A robust explanation of CMB anomalies with a new formulation of inflationary quantum fluctuations
K. Sravan Kumar, João Marto
The presence of CMB Hemispherical Asymmetry (HPA) challenges the current understanding of inflationary cosmology which does not generically predict the parity violation in the prim…
Towards a unitary formulation of quantum field theory in curved spacetime: the case of de Sitter spacetime
K. Sravan Kumar, João Marto
Before we ask what the quantum gravity theory is, it is a legitimate quest to formulate a robust quantum field theory in curved spacetime (QFTCS). Several conceptual problems, espe…
Parity asymmetry of primordial scalar and tensor power spectra
K. Sravan Kumar, João Marto
Although the cosmic microwave background (CMB) is largely understood to be homogeneous and isotropic, the CMB angular power spectra present anomalies that seem to break down parity…
Hawking radiation and black hole gravitational back reaction - A quantum geometrodynamical simplified model
João Marto
The purpose of this paper is to analyse the back reaction problem, between Hawking radiation and the black hole, in a simplified model for the black hole evaporation in the quantum…
A varying Dark Energy effective speed of sound parameter in the phantom Universe
Imanol Albarran, Mariam Bouhmadi-López, João Marto
We analyse the phenomenological effects of a varying Dark Energy (DE) effective speed of sound parameter, , on the cosmological perturbations of three phantom…
Inflaton candidates: from string theory to particle physics
K. Sravan Kumar
Cosmic inflation is the cornerstone of modern cosmology. In particular, following the Planck mission reports presented in 2015 regarding cosmic microwave background (CMB), there is…
Towards nonsingular rotating compact object in ghost-free infinite derivative gravity
Luca Buoninfante, Alan S. Cornell, Gerhard Harmsen +4
The vacuum solution of Einstein's theory of general relativity provides a rotating metric with a ring singularity, which is covered by the inner and outer horizons, and an ergo reg…
Conformally-flat, non-singular static metric in infinite derivative gravity
Luca Buoninfante, Alexey S. Koshelev, Gaetano Lambiase +2
In Einstein's theory of general relativity the vacuum solution yields a blackhole with a curvature singularity, where there exists a point-like source with a Dirac delta distributi…