Dynamical axion misalignment with small instantons

Can Gravitational Instantons Really Constrain Axion Inflation?

Axions play a central role in inflationary model building and other cosmological applications. This is mainly due to their flat potential, which is protected by a global shift symmetry. However, quantum gravity is known to break global symmetries, the crucial effect in the present context being gravitational instantons or Giddings-Strominger wormholes. We attempt to quantify, as model-independe...

The R Axion From Dynamical Supersymmetry Breaking

All generic, calculable models of dynamical supersymmetry breaking have a spontaneously broken R symmetry and therefore contain an R axion. We show that the axion is massive in any model in which the cosmological constant is fine-tuned to zero through an explicit R-symmetry-breaking constant. In visible-sector models, the axion mass is in the 100 MeV range and thus evades astrophysical bounds. ...

Instability in magnetic materials with a dynamical axion field.

It has been pointed out that axion electrodynamics exhibits instability in the presence of a background electric field. We show that the instability leads to a complete screening of an applied electric field above a certain critical value and the excess energy is converted into a magnetic field. We clarify the physical origin of the screening effect and discuss its possible experimental realiza...

Instability in magnetic materials with dynamical axion field

It has been pointed out that the axion electrodynamics exhibits instability in the presence of a background electric field. We show that the instability leads to a complete screening of an applied electric field above a certain critical value and the excess energy is converted into a magnetic field. We clarify the physical origin of the screening effect and discuss its possible experimental rea...

Small Instantons in Matrix Theory