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Stationary Configurations Imply Shift Symmetry: No Bondi Accretion for Quintessence / k-Essence
Ratindranath Akhoury, Christopher S. Gauthier, Alexander Vikman
In this paper we show that, for general scalar fields, stationary configurations are possible for shift symmetric theories only. This symmetry with respect to constant translations…
Inflation with large gravitational waves
Alexander Vikman
It is well known that in manifestly Lorentz invariant theories with nontrivial kinetic terms, perturbations around some classical backgrounds can travel faster than light. These ex…
Enhancing the tensor-to-scalar ratio in simple inflation
V. Mukhanov, A. Vikman
We show that in theories with a nontrivial kinetic term the contribution of the gravitational waves to the CMB fluctuations can be substantially larger than that is naively expecte…
B-Inflation
Alexey Anisimov, Eugeny Babichev, Alexander Vikman
We propose a novel model of inflation based on a large class of covariant effective actions containing only the second derivatives of a scalar field. The initial conditions leading…
Can dark energy evolve to the Phantom?
Alexander Vikman
Dark energy rapidly evolving from the dustlike state in the close past to the phantomlike state at present has been recently proposed as the best fit for the supernovae Ia data. As…