Talk detail

Participant	Garcia-Saenz, Sebastian
Institution	Institut d'Astrophysique de Paris - 98b Boulevard Arago - Paris - Paris - France

Session	EU2	Accepted	Yes	Order	10	Time	18:30	15'
Talk	Oral abstract	Title	Sidetracked Inflation, Orthogonal Non-Gaussianity, and Hyperbolic Field Space
Coauthors	Renaux-Petel, Sebastien; Ronayne, John; Tada, Yuichiro
Abstract	Heavy scalar fields can undergo an instability during inflation as a result of their coupling to the inflatonâ€™s kinetic term. This is known as the geometrical destabilization of inflation, as it relies on the negative curvature of the internal field space overcoming the stabilizing force of the potential. Under some assumptions, this instability can drive the system away from its original path in field space into a new inflationary phase, a scenario that we dub "sidetracked inflation". In this talk I will discuss the physical consequences of this second phase of inflation for several two-field nonlinear sigma models, starting with a general description of the background dynamics and explaining how it differs from the standard slow-roll scenarios. I will next describe our results for the cosmological parameters related to the power spectrum and non-Gaussianity, showing that the effects of the destabilized heavy field can be very significant, leading to important modifications in the observable predictions relative to the single-field expectations. In particular, in the case of a hyperbolic field space, this picture of inflation can give rise to large non-Gaussianities characterized by orthogonal shapes in an unusually generic way.
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Session	AT4	Accepted	Yes	Order	4	Time	16:25	20'
Talk	Oral abstract	Title	A derivation of massive gravity
Coauthors	Boulanger, Nicolas; Deffayet, Cedric; Traina, Lucas
Abstract	Cohomological techniques based on BRST symmetry have proved invaluable for classifying consistent deformations of gauge theories. In this talk I will describe the application of this idea to massive field theories, which are made gauge-invariant by the introduction of Stuckelberg fields. As a first application, we start with a Fierz-Pauli graviton on a maximally symmetric space, and show that the BRST-BV method is able to reproduce the consistent cubic vertices of ghost-free massive gravity. The formalism further sheds light on the characterization of Stuckelberg gauge theories, by demonstrating for instance that the gauge algebra of such models is Abelian and that they admit a Born-Infeld type formulation in which the action is simply a combination of gauge-invariant structures.
Pdf file