Gravity wave and model-independent axion

Solitons of axion-dilaton gravity.

We use soliton techniques of the two-dimensional reduced β-function equations to obtain non-trivial string backgrounds from flat space. These solutions are characterized by two integers (n,m) referring to the soliton numbers of the metric and axion-dilaton sectors respectively. We show that the NappiWitten universe associated with the SL(2) × SU(2)/SO(1, 1) × U(1) CFT coset arises as an (1, 1) ...

Hidden sector gaugino condensation and the model-independent axion

Wave propagation in axion electrodynamics

In this paper, the axion contribution to the electromagnetic wave propagation is studied. First we show how the axion electrodynamics model can be embedded into a premetric formalism of Maxwell electrodynamics. In this formalism, the axion field is not an arbitrary added Chern-Simon term of the Lagrangian, but emerges in a natural way as an irreducible part of a general constitutive tensor. We ...

Stationary BPS solutions to dilaton-axion gravity.

Stationary four-dimensional BPS solutions to gravity coupled bosonic theories admitting a three–dimensional sigma–model representation on coset spaces are interpreted as null geodesics of the target manifold equipped with a certain number of harmonic maps. For asymptotically flat (or Taub–NUT) space–times such geodesics can be directly parametrized in terms of charges saturating the Bogomol’nyi...

Resonant Gravitational Wave Amplification - Axion and Inflaton

The nature of the cosmological background of gravitational waves is a subject of great interest at present, with many possible sources ranging from quantum fluctuations in a string-dominated phase 1,2 or inflation , to oscillations of cosmic string loops . Here we focus instead on a powerful mechanism for distortion and amplification of any existing gravitational wave background namely damped p...