Antonio Padilla
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View article: Higher co-dimension de Sitter branes
Higher co-dimension de Sitter branes Open
We extend the arguments of Maldacena and Núñez to include higher co-dimension brane setups and derive a new no-go theorem. Specifically, we show that under reasonable assumptions on the energy-momentum conservation and the bulk curvature, …
View article: Stückelberg path to pure de Sitter supergravity
Stückelberg path to pure de Sitter supergravity Open
We advance the study of pure de Sitter supergravity by introducing a finite formulation of unimodular supergravity via the super-Stückelberg mechanism. Building on previous works, we construct a complete four-dimensional action of spontane…
View article: Stückelberg path to pure de Sitter supergravity
Stückelberg path to pure de Sitter supergravity Open
We advance the study of pure de Sitter supergravity by introducing a finite formulation of unimodular supergravity via the super-Stückelberg mechanism. Building on previous works, we construct a complete four-dimensional action of spontane…
View article: Do we live on the End of the World?
Do we live on the End of the World? Open
A bstract We propose a scenario of a de Sitter universe living on an End-of-the-World brane. Motivated by the Swampland programme and in particular the Cobordism Conjecture, we consider a compact region of AdS 5 nucleating from nothing, wi…
View article: Neutron stars and the cosmological constant problem
Neutron stars and the cosmological constant problem Open
Phase transitions can play an important role in the cosmological constant problem, allowing the underlying vacuum energy, and therefore the value of the cosmological constant, to change. Deep within the core of neutron stars, the local pre…
View article: Horndeski speed tests with scalar-photon couplings
Horndeski speed tests with scalar-photon couplings Open
We revisit multi-messenger constraints from neutron star mergers on the speed of propagation of gravitational and electromagnetic waves in Horndeski and beyond Horndeski theories. By considering non-trivial couplings between the dark energ…
View article: Gauge invariance and generalised $η$ regularisation
Gauge invariance and generalised $η$ regularisation Open
We generalise the $η$ regularisation scheme in order to develop a framework for systematically studying regularisation of loops in quantum field theory. This allows us to "solve" a set of gauge consistency conditions for families of gauge …
View article: Do we live on the End of the World?
Do we live on the End of the World? Open
We propose a scenario of a de Sitter universe living on an End-of-the-World brane. Motivated by the Swampland programme and in particular the Cobordism Conjecture, we consider a compact region of AdS$_5$ nucleating from nothing, with a dS$…
View article: From inflation to quintessence: a history of the universe in string theory
From inflation to quintessence: a history of the universe in string theory Open
A bstract We present a type IIB 4D string model with stabilised moduli which is able to describe the history of the universe from inflation to quintessence. The underlying Calabi-Yau volume is controlled by two moduli which are stabilised …
View article: de Sitter vacua in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="normal">O</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>d</mml:mi><mml:mo>,</mml:mo><mml:mi>d</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:math> invariant cosmology
de Sitter vacua in invariant cosmology Open
We perform a thorough analysis of de Sitter solutions in O(d,d) invariant cosmologies. Starting with a homogeneous and isotropic framework we examine conditions for the existence of such solutions to the vacuum field equations, nonperturba…
View article: Horndeski speed tests with scalar-photon couplings
Horndeski speed tests with scalar-photon couplings Open
We revisit multi-messenger constraints from neutron star mergers on the speed of propagation of gravitational and electromagnetic waves in Horndeski and beyond Horndeski theories. By considering non-trivial couplings between the dark energ…
View article: Smoothed asymptotics: From number theory to QFT
Smoothed asymptotics: From number theory to QFT Open
Inspired by the method of smoothed asymptotics developed by Terence Tao, we introduce a new ultraviolet regularization scheme for loop integrals in quantum field theory which we call η regularization. This reveals a connection between the …
View article: From Inflation to Quintessence: a History of the Universe in String Theory
From Inflation to Quintessence: a History of the Universe in String Theory Open
We present a type IIB 4D string model with stabilised moduli which is able to describe the history of the universe from inflation to quintessence. The underlying Calabi-Yau volume is controlled by two moduli which are stabilised by perturb…
View article: Neutron stars and the cosmological constant problem
Neutron stars and the cosmological constant problem Open
Phase transitions can play an important role in the cosmological constant problem, allowing the underlying vacuum energy, and therefore the value of the cosmological constant, to change. Deep within the core of neutron stars, the local pre…
View article: On de Sitter vacua in O(d,d) invariant cosmology
On de Sitter vacua in O(d,d) invariant cosmology Open
We perform a thorough analysis of de Sitter vacua in O(d,d) invariant cosmologies. Starting with a homogeneous and isotropic framework we examine conditions for the existence of such vacua, non-perturbative in α' in both the string frame a…
View article: Ringdowns for black holes with scalar hair: The large mass case
Ringdowns for black holes with scalar hair: The large mass case Open
Deviations from general relativity can alter the quasinormal mode (QNM) ringdown of perturbed black holes. It is known that a shift-symmetric (hence massless) scalar can only introduce black hole hair if it couples to the Gauss-Bonnet inva…
View article: The cosmological constant and the weak gravity conjecture
The cosmological constant and the weak gravity conjecture Open
We examine the descent via membrane nucleation through a landscape of vacua where the cosmological constant is given by a combination of four-form fluxes. It has been shown that this descent can be slowed exponentially for very low curvatu…
View article: Smoothed asymptotics: from number theory to QFT
Smoothed asymptotics: from number theory to QFT Open
Inspired by the method of smoothed asymptotics developed by Terence Tao, we introduce a new ultra-violet regularisation scheme for loop integrals in quantum field theory which we call $η$ regularisation. This allows us to reveal a surprisi…
View article: Ringdowns for black holes with scalar hair: the large mass case
Ringdowns for black holes with scalar hair: the large mass case Open
Deviations from General Relativity can alter the quasi-normal mode (QNM) ringdown of perturbed black holes. It is known that a shift-symmetric (hence massless) scalar can only introduce black hole hair if it couples to the Gauss-Bonnet inv…
View article: The cosmological constant is probably still zero
The cosmological constant is probably still zero Open
A bstract We consider a wide class of four-dimensional effective field theories in which gravity is coupled to multiple four-forms and their dual scalar fields, with membrane sources charged under the corresponding three-form potentials. F…
View article: The cosmological constant is probably still zero
The cosmological constant is probably still zero Open
We consider a wide class of four-dimensional effective field theories in which gravity is coupled to multiple four-forms and their dual scalar fields, with membrane sources charged under the corresponding three-form potentials. Four-form f…
View article: CMB constraints on monodromy inflation at strong coupling
CMB constraints on monodromy inflation at strong coupling Open
We carry out a thorough numerical examination of field theory monodromy inflation at strong coupling. We perform an MCMC analysis using a Gaussian likelihood, fitting multiparameter models using CMB constraints on the spectral index and th…
View article: An étude on global vacuum energy sequester
An étude on global vacuum energy sequester Open
Recently two of the authors proposed a mechanism of vacuum energy sequester as a means of protecting the observable cosmological constant from quantum radiative corrections. The original proposal was based on using global Lagrange multipli…
View article: Generalised scalar-tensor theories and self-tuning
Generalised scalar-tensor theories and self-tuning Open
We explore a family of generalised scalar-tensor theories that exhibit self-tuning to low scale anti de Sitter vacua, even in the presence of a large cosmological constant. We are able to examine the linearised fluctuations about these vac…
View article: Quintessence and the Swampland: The Numerically Controlled Regime of Moduli Space
Quintessence and the Swampland: The Numerically Controlled Regime of Moduli Space Open
We provide a detailed discussion of the main theoretical and phenomenological challenges of quintessence model building in any numerically controlled regime of the moduli space of string theory. We argue that a working quintessence model r…
View article: Quintessence and the Swampland: The Parametrically Controlled Regime of Moduli Space
Quintessence and the Swampland: The Parametrically Controlled Regime of Moduli Space Open
We provide evidence that slow roll is not possible in any parametrically controlled regime of the moduli space of string theory. This is proven in full generality in the asymptotic limit of the moduli space of type II and heterotic Calabi‐…
View article: Quintessence and the Swampland: The numerically controlled regime of moduli space
Quintessence and the Swampland: The numerically controlled regime of moduli space Open
We provide a detailed discussion of the main theoretical and phenomenological challenges of quintessence model building in any numerically controlled regime of the moduli space of string theory. We argue that a working quintessence model r…
View article: Quadratic curvature corrections to stringy effective actions and the absence of de Sitter vacua
Quadratic curvature corrections to stringy effective actions and the absence of de Sitter vacua Open
We investigate the combined effect of fluxes and higher-order curvature corrections, in the form of the Gauss-Bonnet term, on the existence of de Sitter vacua in a heterotic string inspired framework, compactified on spheres and tori. We f…