Théorie

Vacuum stability without Supersymmetry: Brane dynamics, bubbles and holography

n this talk I will present some recent results on instabilities of anti-de Sitter flux compactifications in effective field theories arising from non-supersymmetric string models, namely the USp(32) and U(32) orientifold models and the SO(16) x SO(16) heterotic string. We focus on non-perturbative instabilities, framing the vacua in terms of brane stacks, analyzing their back-reacted geometry and reproducing AdS its near-horizon limit.

Miniworkshop on Holographic QCD at high densities, neutron stars and gravitational waves

This one-day workshop will bring together theorists working on the AdS/CFT correspondence, nuclear physics, and General Relativity for an interdisciplinarly exchange aimed at developing a consistent holographic picture of QCD matter at high density, from model building to the description of compact objects and observation via gravitational wave signals. Invited speakers include: Umut Gursoy (Utrecht U); Matti Jarvinen (Utrecht U. and Tel Aviv U.); Niko Jokela (Helsinki U.); Micaela Oertel (LUTH); Eric Gourgoulhon (LUTH). 

Programme:

Non-Fierz-Pauli bimetric theory from quadratic curvature gravity on Einstein manifolds

I will show that, in four-dimensional spacetimes with an arbitrary
Einstein metric, with and without a cosmological constant, perturbative dynamical degrees of freedom in generic quadratic-curvature gravity can be decoupled into massless and massive parts. The massive part has the structure iden-ical to, modulo the

Stability properties in mimetic gravity theories

Motivated as a possible unified description for dark matter and dark
energy, we analyze the cosmological applications and the stability
conditions of Mimetic Gravity models. In connection to the fact that
these models have been recently shown to be plagued by instabilities, we
show that for the original mimetic matter model the ghost/tachyon instability
for perturbations around the FLRW background can be interpreted as the
standard Jeans instability of dust.
Proposed as a solution for the instability problems, we discuss mimetic

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