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M. Marco PELOSO (University of Minnesota)AbsractsAxion inflation is a natural class of models of inflation, in which the flatness of the inflaton potential is protected against quantum correction by an approximate shift symmetry. The symmetry highly constrains the couplings of the inflaton to other fields. The allowed coupling to vector fields produces an amplification of these fields, exponentially proportional to thespeed of the...Go to contribution page
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M. Sébastien CLESSE (RWTH Aachen University)AbsractsThe recent detection by Advanced-LIGO/VIRGO of gravitational waves (GW) from the merging of binary black hole systems sets new limits on the merging rates of massive primordial black holes (PBH) that could be identified to the dark matter in the Universe. If PBH are regrouped in clusters with a similar density to the one observed in ultra-faint dwarf galaxies, merging rates are comparable to...Go to contribution page
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Dr Ilia Musco (LUTH, Observatoire de Paris (Meudon))AbsractsCosmological perturbations could collapse after horizon crossing giving rise to primordial black holes (PBHs) in the early universe if the perturbation amplitude is large enough to overcome a critical threshold depending on the equation of state and the density profile. In this talk I will present results coming from numerical simulations of PBH formation, where a time independent curvature...Go to contribution page
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M. Francesco Di Renzo (INFN Pisa)AbsractsIn this talk, we present a generalized algorithm for the detection of a stationary, isotropic and Gaussian SGWB with non-standard polarizations, as predicted by many alternative theories of gravity and cosmological models. We follow a frequentist approach that is suitable when no prior knowledge is available about alternative theories and hitherto unclear production mechanisms. We compute the...Go to contribution page
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Dr philippe brax (IPHT Saclay)AbsractsI would like to discuss the physics of gravitational birefringence as it appears in bigravity models.Go to contribution page
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M. Thomas Schucker (CPT Marseille)AbsractsThe trajectory of light in a flat Robertson-Walker universe is presented taking due account of its spin. The off-set between the trajectories of positive and negative helicity states (birefringence) is of the order of a wave length and depends on the acceleration parameter. In 2008, using techniques of weak quantum measurement, an analogous birefringence in reflection, the Federov-Imbert...Go to contribution page
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M. Daniel FIGUEROA (CERN, Theory Dept.)AbsractsI will discuss the irreducible emission of gravitational waves by any cosmic defect network, and its observational consequences.Go to contribution page
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Dr Stefano Orani (University of Basel)AbsractsI will talk about the production of gravitational waves during preheating after inflation in the common case of field potentials that are asymmetric around the minimum. In particular, I will present a study of the impact of oscillons, comparatively long lived and spatially localized regions where a scalar field (e.g. the inflaton) oscillates with large amplitude. Oscillons in asymmetric...Go to contribution page
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Ido Ben-Dayan (Ben Gurion University)AbsractsWe calculate the gravitational waves (GW) spectrum produced in various Early Universe scenarios from gauge field sources, thus generalizing earlier inflationary calculations to bouncing cosmologies. We consider generic couplings between the gauge fields and the scalar field dominating the energy density of the Universe. Due to this coupling a sourced GW spectrum is generated. For certain...Go to contribution page
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M. Sebastian Cespedes (Damtp, Universiyt of Cambridge)AbsractsWe will discuss the effects that a modified sector tensor can produce on the polarisation CMB power spectra. Alternative theories of gravity can give the graviton a mass but also modify the dispersion relation of the gravitational waves. by A mass for the graviton can affect the large angular scales and in general a modified dispersion relation could change the position of the acoustic...Go to contribution page
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Dr Lukas Witkowski (APC)AbsractsOne common feature of models of axion inflation is the existence of instantonic modulations, which can give rise to a series of local minima in the post-inflationary region of the potential. The inflaton can then populate more than one of these vacua inside a single Hubble patch, which corresponds to a dynamical phase decomposition. In the subsequent process of bubble wall collisions, the...Go to contribution page
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Mme Ivonne Zavala (Swansea University)AbsractsI will discuss the status and challenges of string they inflationary models, which can potentially produce detectable primordial gravitational waves. I will illustrate these aspects in terms of axion inflation in string theory models.Go to contribution page
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Gianmassimo Tasinato (Swansea Uni)AbsractsSupersolid inflation corresponds a class of inflationary theories which spontaneously break both time and space reparameterization invariance during inflation. I will discuss cosmological fluctuations in such scenarios, focussing on the dynamics of inflationary tensor modes, and including tensor non Gaussianities. Tensor modes can have a blue spectrum, and primordial tensor non...Go to contribution page
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Dr Sébastien Renaux-Petel (IAP-CNRS)AbsractsI will describe the consequences of a recently discovered instability at play in the early universe. The so-called Geometrical Destabilization of inflation is a general mechanism by which the curvature of the field space of inflationary models can dominate the stabilizing forces from the potential and destabilize inflationary trajectories. This instability is present in lots of concrete...Go to contribution page
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Mme Tania REGIMBAU (Observatoire de la Cote d'Azur)AbsractsAccording to various cosmological scenarios, we are bathed in a stochastic background of gravitational waves generated in the first instants after the Big Bang. This background is based on the amplification of vacuum fluctuations during inflation, as well as on additional GW radiation produced in the final stages of inflation (for example in preheating models or models of axion inflation)....Go to contribution page
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