Di Valentino, Eleonora Melchiorri, Alessandro Silk, Joseph

We show that a combined analysis of CMB anisotropy power spectra obtained by the Planck satellite and luminosity distance data simultaneously excludes a flat universe and a cosmological constant at $99 \%$ C.L. These results hold separately when combining Planck with three different datasets: the two determinations of the Hubble constant from Riess...

Benedetti, Dario Carrozza, Sylvain Toriumi, Reiko Valette, Guillaume

We study the double- and triple-scaling limits of a complex multi-matrix model, with $\mathrm{U}(N)^2\times \mathrm{O}(D)$ symmetry. The double-scaling limit amounts to taking simultaneously the large-$N$ (matrix size) and large-$D$ (number of matrices) limits while keeping the ratio $N/\sqrt{D}=M$ fixed. The triple-scaling limit consists in taking...

Levi, Michèle McLeod, Andrew J. Von Hippel, Matthew

In this paper we derive for the first time the NNNLO gravitational spin-orbit coupling at the quartic order in G in the post-Newtonian (PN) approximation. This represents the first computation in a spinning sector involving three-loop integration. We provide a comprehensive account of the topologies in the worldline picture for the computation, whi...

Chavanis, Pierre-Henri

We compute the quantum tunneling rate of dilute axion stars close to the maximum mass [P.H. Chavanis, Phys. Rev. D {\bf 84}, 043531 (2011)] using the theory of instantons. We confirm that the lifetime of metastable states is extremely long, scaling as $t_{\rm life}\sim e^N\, t_D$ (except close to the critical point), where $N$ is the number of axio...

Kuntz, Adrien

We show that the introduction of two worldline parameters allows to drastically simplify computations in the effective field theory approach to the two-body problem in General Relativity, effectively removing half of the complexity in Feynman diagrams. These parameters obey a polynomial equation whose perturbative expansion recovers an infinite ser...

Brax, Philippe Heisenberg, Lavinia Kuntz, Adrien

We consider the prospect of detecting cubic Galileons through their imprint on gravitational wave signals from a triple system. Namely, we consider a massive Black Hole (BH) surrounded by a binary system of two smaller BHs. We assume that the three BHs acquire a conformal coupling to the scalar field whose origin could be due to cosmology or to the...

Abreu, S. Febres Cordero, F. Ita, H. Jaquier, M. Page, B. Ruf, M.S. Sotnikov, V.

We present the analytic form of the two-loop four-graviton scattering amplitudes in Einstein gravity. To remove ultraviolet divergences we include counterterms quadratic and cubic in the Riemann curvature tensor. The two-loop numerical unitarity approach is used to deal with the challenging momentum dependence of the interactions. We exploit the al...

Antoniadis, Ignatios Lykkas, Angelos Tamvakis, Kyriakos

We consider models of a scalar field coupled to quadratic $R\!+\!R^2$ gravity in the framework of the Palatini formulation. The resulting Einstein-frame generalized $k$-inflation effective theory is analyzed assuming that the constant-roll condition holds. We focus on a quartic self-interaction potential, a case of particular appeal modelling Higgs...

Dietrich, Tim Coughlin, Michael W. Pang, Peter T.H. Bulla, Mattia Heinzel, Jack Issa, Lina Tews, Ingo Antier, Sarah

Neutron-star mergers are associated with violent phenomena that probe physical principles under extreme conditions that are not reproducible in any terrestrial laboratory. Thus, their multi-messenger analysis combining gravitational-wave and electromagnetic signatures from multiple wavelengths is not only of astrophysical interest, but it also allo...

Marsat, Sylvain Baker, John G. Dal Canton, Tito

The space-based gravitational wave detector LISA will observe mergers of massive black hole binary systems (MBHBs) to cosmological distances, as well as inspiralling stellar-origin (or stellar-mass) binaries (SBHBs) years before they enter the LIGO/Virgo band. Much remains to be explored for the parameter recovery of both classes of systems. Previo...