Scalar field
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Early Dark Energy can Resolve the Hubble Tension Open
Early dark energy (EDE) that behaves like a cosmological constant at early times (redshifts z≳3000) and then dilutes away like radiation or faster at later times can solve the Hubble tension. In these models, the sound horizon at decouplin…
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Dark Energy after GW170817 and GRB170817A Open
The observation of GW170817 and its electromagnetic counterpart implies that gravitational waves travel at the speed of light, with deviations smaller than a few×10^{-15}. We discuss the consequences of this experimental result for models …
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Extended scalar-tensor theories of gravity Open
We study new consistent scalar-tensor theories of gravity recently introduced\nby Langlois and Noui with potentially interesting cosmological applications. We\nderive the conditions for the existence of a primary constraint that prevents\n…
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Planck 2015 results:XIV. Dark energy and modified gravity Open
We study the implications of Planck data for models of dark energy (DE) and modified gravity (MG) beyond the standard cosmological constant scenario. We start with cases where the DE only directly affects the background evolution, consider…
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Steepest growth of the power spectrum and primordial black holes Open
We derive analytic bounds on the shape of the primordial power spectrum in the context of single-field inflation. In particular, the steepest possible growth has a spectral index of ns − 1 = 4 once transients have died down. Its primary im…
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Dynamical boson stars Open
The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s, John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called geons , but none were found. I…
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Degenerate higher order scalar-tensor theories beyond Horndeski and disformal transformations Open
We consider all degenerate scalar-tensor theories that depend quadratically\non second order derivatives of a scalar field, which we have identified in a\nprevious work. These theories, whose degeneracy in general ensures the absence\nof O…
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Quasinormal Modes and Strong Cosmic Censorship Open
The fate of Cauchy horizons, such as those found inside charged black holes, is intrinsically connected to the decay of small perturbations exterior to the event horizon. As such, the validity of the strong cosmic censorship (SCC) conjectu…
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Kerr black holes with Proca hair Open
Bekenstein proved that in Einstein's gravity minimally coupled to one (or\nmany) real, Abelian, Proca field, stationary black holes (BHs) cannot have\nProca hair. Dropping Bekenstein's assumption that matter inherits spacetime\nsymmetries,…
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Dark energy and modified gravity in degenerate higher-order scalar–tensor (DHOST) theories: A review Open
This paper reviews scalar–tensor theories characterized by a Lagrangian that, despite the presence of second-order derivatives, contains a single scalar degree of freedom. These theories, known as Degenerate Higher-Order Scalar–Tensor (DHO…
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Single field double inflation and primordial black holes Open
Within the framework of scalar-tensor theories, we study the conditions that allow single field inflation dynamics on small cosmological scales to significantly differ from that of the large scales probed by the observations of cosmic micr…
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Early Dark Energy from Massive Neutrinos as a Natural Resolution of the Hubble Tension Open
The Hubble tension can be significantly eased if there is an early component of dark energy that becomes active around the time of matter-radiation equality. Early dark energy models suffer from a coincidence problem-the physics of matter-…
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Scalaron from <i>R</i><sup>2</sup>-gravity as a heavy field Open
We study a model of inflation in which a scalar field $\chi$ is non-minimally coupled to Starobinsky's $R^2$ gravity. After transforming it to the Einstein frame, a new scalar field, the scalaron $\phi$, will appear and couple to $\chi$ wi…
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Scalar-tensor theories and modified gravity in the wake of GW170817 Open
Theories of dark energy and modified gravity can be strongly constrained by astrophysical or cosmological observations, as illustrated by the recent observation of the gravitational wave event GW170817 and of its electromagnetic counterpar…
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Support-free volume printing by multi-axis motion Open
This paper presents a new method to fabricate 3D models on a robotic printing system equipped with multi-axis motion. Materials are accumulated inside the volume along curved tool-paths so that the need of supporting structures can be trem…
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Light–matter interaction in the long-wavelength limit: no ground-state without dipole self-energy Open
Most theoretical studies for correlated light-matter systems are performed within the long-wavelength limit, i.e., the electromagnetic field is assumed to be spatially uniform. In this limit the so-called length-gauge transformation for a …
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Stochastic and Resolvable Gravitational Waves from Ultralight Bosons Open
Ultralight scalar fields around spinning black holes can trigger superradiant instabilities, forming a long-lived bosonic condensate outside the horizon. We use numerical solutions of the perturbed field equations and astrophysical models …
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Accurate interatomic force fields via machine learning with covariant kernels Open
We present a novel scheme to accurately predict atomic forces as vector\nquantities, rather than sets of scalar components, by Gaussian Process (GP)\nRegression. This is based on matrix-valued kernel functions, on which we impose\nthe requ…
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Searching for an Oscillating Massive Scalar Field as a Dark Matter Candidate Using Atomic Hyperfine Frequency Comparisons Open
International audience
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Versatile rogue waves in scalar, vector, and multidimensional nonlinear systems Open
This review is dedicated to recent progress in the active field of rogue waves, with an emphasis on the analytical prediction of versatile rogue wave structures in scalar, vector, and multidimensional integrable nonlinear systems. We first…
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Anomalies in the space of coupling constants and their dynamical applications I Open
It is customary to couple a quantum system to external classical fields. One application is to couple the global symmetries of the system (including the Poincaré symmetry) to background gauge fields (and a metric for the Poincaré symmetry)…
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Superfluid Black Holes Open
We present what we believe is the first example of a "λ-line" phase transition in black hole thermodynamics. This is a line of (continuous) second order phase transitions which in the case of liquid ^{4}He marks the onset of superfluidity.…
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<i>MICROSCOPE</i> Mission: First Constraints on the Violation of the Weak Equivalence Principle by a Light Scalar Dilaton Open
The existence of a light or massive scalar field with a coupling to matter weaker than gravitational strength is a possible source of violation of the weak equivalence principle. We use the first results on the Eötvös parameter by the MICR…
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Gravitational waves from vacuum first-order phase transitions: From the envelope to the lattice Open
Movie based on Figure 2 of the paper Gravitational waves from vacuum first-order phase transitions: from the envelope to the lattice [arXiv:1802.05712]. This movie originally appeared as Supplemental Material associated with the paper. Cap…
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High-accuracy phase-field models for brittle fracture based on a new family of degradation functions Open
Phase-field approaches to fracture based on energy minimization principles have been rapidly gaining popularity in recent years, and are particularly well-suited for simulating crack initiation and growth in complex fracture networks. In t…
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Recent Advances in Inflation Open
We review recent trends in inflationary dynamics in the context of viable modified gravity theories. After providing a general overview of the inflationary paradigm emphasizing on what problems hot Big Bang theory inflation solves, and a s…
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Electroweak baryogenesis and gravitational waves from a real scalar singlet Open
We consider a real scalar singlet field which provides a strong first-order\nelectroweak phase transition via its coupling to the Higgs boson, and gives a\n$CP$ violating contribution on the top quark mass via a dimension-6 operator.\nWe s…
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Notes on the complex Sachdev-Ye-Kitaev model Open
We describe numerous properties of the Sachdev-Ye-Kitaev model for complex fermions withN$\\gg$ 1 flavors and a global U(1) charge. We provide a general definition of the charge in the (G,Σ) formalism, and compute its universal relation to…
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Bouncing cosmology in f(Q) symmetric teleparallel gravity Open
We consider f ( Q ) extended symmetric teleparallel cosmologies, where Q is the non-metricity scalar, and constrain its functional form through the order reduction method. By using this technique, we are able to reduce and integrate the fi…
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Spontaneous scalarization with massive fields Open
We study the effect of a mass term in the spontaneous scalarization of neutron stars, for a wide range of scalar field parameters and neutron star equations of state. Even though massless scalars have been the focus of interest in spontane…