Philippe Brax
YOU?
Author Swipe
View article: Testing scalar dark matter clumps with pulsar timing arrays
Testing scalar dark matter clumps with pulsar timing arrays Open
International audience
View article: Screened axio-dilaton cosmology: novel forms of early dark energy
Screened axio-dilaton cosmology: novel forms of early dark energy Open
View article: Weinberg’s theorem, phantom crossing, and screening
Weinberg’s theorem, phantom crossing, and screening Open
We consider models where the dilaton, seen as the pseudo-Goldstone boson of broken scale invariance, plays the role of dark energy. We revisit Weinberg's theorem and show that quantum corrections induced by the graviton lead to the screeni…
View article: A minimal axio-dilaton dark sector
A minimal axio-dilaton dark sector Open
In scalar-tensor theories it is the two-derivative sigma-model interactions that like to compete at low energies with the two-derivative interactions of General Relativity (GR) — at least once the dangerous zero-derivative terms of the sca…
View article: Casimir pressure with dissipation and quantum corrections from axion dark matter
Casimir pressure with dissipation and quantum corrections from axion dark matter Open
We study the effects of the oscillating axion field present in our environment on the Casimir pressure between two metallic plates. We take into account the finite conductivity of the boundary plates and model the interactions between matt…
View article: Primordial gravitational waves in DHOST inflation
Primordial gravitational waves in DHOST inflation Open
We consider DHOST inflationary models with a shift symmetry leading to a de Sitter space–time at the background cosmological level. Deviations from scale invariance of the scalar and tensor perturbations follow from the breaking of the shi…
View article: Formation of solitons and their transitions in scalar-field dark matter models with a nonpolynomial self-interaction potential
Formation of solitons and their transitions in scalar-field dark matter models with a nonpolynomial self-interaction potential Open
We study the formation of solitons inside scalar-field dark matter halos with a non-polynomial self-interaction potential. We consider a self-interaction potential that is quartic in the scalar field in the low-density regime but saturates…
View article: Running Love Numbers and the Effective Field Theory of Gravity
Running Love Numbers and the Effective Field Theory of Gravity Open
Massive states produce higher derivative corrections to Einstein gravity in the infrared, which are encoded into operators of the Effective Field Theory (EFT) of gravity. These EFT operators modify the geometry and affect the tidal propert…
View article: Vortices and rotating solitons in ultralight dark matter
Vortices and rotating solitons in ultralight dark matter Open
The dynamics of ultralight dark matter with non-negligible self-interactions are determined by a nonlinear Schrödinger equation rather than by the Vlasov equation of collisionless particles. This leads to wave-like effects, such as interfe…
View article: CMB implications of multi-field axio-dilaton cosmology
CMB implications of multi-field axio-dilaton cosmology Open
Axio-dilaton models are among the simplest scalar-tensor theories that contain the two-derivative interactions that naturally compete at low energies with the two-derivative interactions of General Relativity. Such models are well-motivate…
View article: Resilience of DBI screened objects and their ladder symmetries
Resilience of DBI screened objects and their ladder symmetries Open
View article: A Minimal Axio-dilaton Dark Sector
A Minimal Axio-dilaton Dark Sector Open
In scalar-tensor theories it is the two-derivative sigma-model interactions that like to compete at low energies with the two-derivative interactions of General Relativity (GR) $\unicode{x2014}$ at least once the dangerous zero-derivative …
View article: Detecting dark matter oscillations with gravitational waveforms
Detecting dark matter oscillations with gravitational waveforms Open
We consider the phase shift in the gravitational wave signal induced by fast oscillations of scalar dark matter surrounding binary systems, which could be probed by the future experiments LISA and DECIGO. This effect depends on the local m…
View article: <i>Euclid</i>: Constraining linearly scale-independent modifications of gravity with the spectroscopic and photometric primary probes
<i>Euclid</i>: Constraining linearly scale-independent modifications of gravity with the spectroscopic and photometric primary probes Open
Context . The future Euclid space satellite mission will offer an invaluable opportunity to constrain modifications to Einstein’s general relativity at cosmic scales. In this paper, we focus on modified gravity models characterised, at lin…
View article: Classical Casimir pressure in the presence of axion dark matter
Classical Casimir pressure in the presence of axion dark matter Open
We study the effects of an oscillating axion field on the pressure between two metallic plates. We consider the situation where a magnetic field parallel to the plates is present and show that the electric field induced by the coupling of …
View article: CMB Implications of Multi-field Axio-dilaton Cosmology
CMB Implications of Multi-field Axio-dilaton Cosmology Open
Axio-dilaton models are among the simplest scalar-tensor theories that contain the two-derivative interactions that naturally compete at low energies with the two-derivative inter-actions of General Relativity. Such models are well-motivat…
View article: Resilience of DBI screened objects and their ladder symmetries
Resilience of DBI screened objects and their ladder symmetries Open
Scalar field theories with a shift symmetry come equipped with the $K$-mouflage (or kinetic screening) mechanism that suppresses the scalar interaction between massive objects below a certain distance, the screening radius. In this work, w…
View article: Casimir Forces in CFT with Defects and Boundaries
Casimir Forces in CFT with Defects and Boundaries Open
We investigate the quantum forces occurring between the defects and/or boundaries of a conformal field theory (CFT). We propose to model imperfect defects and boundaries as localized relevant double-trace operators that deform the CFT. Our…
View article: CMB bispectrum constraints on DHOST inflation
CMB bispectrum constraints on DHOST inflation Open
We present the first direct constraints on a Degenerate Higher Order Scalar Tensor (DHOST) inflation model using the Planck 2018 Cosmic Microwave Background (CMB) results on non-Gaussianities. We identify that the bispectrum consists of a …
View article: Solitons and halos for self-interacting scalar dark matter
Solitons and halos for self-interacting scalar dark matter Open
We study the formation and evolution of solitons supported by repulsive self-interactions inside extended halos, for scalar-field dark matter scenarios. We focus on the semiclassical regime where the quantum pressure is typically much smal…
View article: Gravitational waves from binary black holes in a self-interacting scalar dark matter cloud
Gravitational waves from binary black holes in a self-interacting scalar dark matter cloud Open
We investigate the imprints of accretion and dynamical friction on the gravitational-wave signals emitted by binary black holes embedded in a scalar dark matter cloud. As a key feature in this work, we focus on scalar fields with a repulsi…
View article: Search for environment-dependent dilatons
Search for environment-dependent dilatons Open
International audience
View article: CMB bispectrum constraints on DHOST inflation
CMB bispectrum constraints on DHOST inflation Open
We present the first direct constraints on a Degenerate Higher Order Scalar Tensor (DHOST) inflation model using the Planck 2018 Cosmic Microwave Background (CMB) results on non-Gaussianities. We identify that the bispectrum consists of a …
View article: New insights on ν–DM interactions
New insights on ν–DM interactions Open
We revisit the possibility of using cosmological observations to constrain models that involve interactions between neutrinos and dark matter. We show that small-scale measurements of the cosmic microwave background (CMB) with a few per ce…
View article: Multiscale constraints on scalar-field couplings to matter: The geodetic and frame-dragging effects
Multiscale constraints on scalar-field couplings to matter: The geodetic and frame-dragging effects Open
The impact of light scalars coupled conformally and disformally to matter on the geodetic and frame-dragging precessions is calculated. For larger frequencies the disformal interaction becomes increasingly relevant. We use several satellit…
View article: Scalaron dynamics from UV to IR
Scalaron dynamics from UV to IR Open
We consider a scenario where the scalaron of $f({\cal R})$ models is related to the volume modulus of string compactifications leaving only one scalar degree of freedom at low energy. The coefficient of the leading curvature squared contri…
View article: Two-field screening and its cosmological dynamics
Two-field screening and its cosmological dynamics Open
We consider the screening of the axio-dilaton fields when both the dilaton and the axion couple to matter with Yukawa couplings. We analyze the screening of the dilaton in the vicinity of a compact object and find that this can only take p…
View article: Extended analysis of neutrino-dark matter interactions with small-scale CMB experiments
Extended analysis of neutrino-dark matter interactions with small-scale CMB experiments Open
View article: Light axiodilatons: matter couplings, weak-scale completions and long-distance tests of gravity
Light axiodilatons: matter couplings, weak-scale completions and long-distance tests of gravity Open
We consider the physical implications of very light axiodilatons motivated by a novel mechanism to substantially reduce the vacuum energy proposed in 2110.10352 . We address the two main problems concerning the light axiodilaton that appea…
View article: Supersonic friction of a black hole traversing a self-interacting scalar dark matter cloud
Supersonic friction of a black hole traversing a self-interacting scalar dark matter cloud Open
Black Holes (BH) traversing a dark matter cloud made out of a self-interacting scalar soliton are slowed down by two complementary effects. At low subsonic speeds, the BH accretes dark matter and this is the only source of dragging along i…