Tuesdays 10:30 - 11:30 | Fridays 11:30 - 12:30
Showing votes from 2015-06-09 11:30 to 2015-06-12 12:30 | Next meeting is Friday Jul 10th, 11:30 am.
We uncover a large class of infinitesimal, but fully nonlinear in the field, symmetries obeyed by a restricted family of Galileon theories in any dimension and elucidate their structure. The symmetry transformation involves powers of the coordinates $x$ and the field $\pi$ up to any finite order $N$. Up to quadratic order the structure of these new symmetry transformations is the unique generalisation of both the infinitesimal version of the standard Galileon shift symmetry as well as a recently discovered infinitesimal extension of this symmetry and we derive higher order analogues for the first time.
Models of large-field inflation based on axion-like fields with shift symmetries can be simple and natural, and make a promising prediction of detectable primordial gravitational waves. The Weak Gravity Conjecture is known to constrain the simplest case in which a single axion descends from a gauge field in an extra dimension. By supplementing the Weak Gravity Conjecture with considerations of how the mass spectrum of the theory varies across the axion moduli space, we obtain more powerful constraints that apply to a variety of multi-axion theories including N-flation and alignment models. In every case that we consider, plausible assumptions lead to field ranges that cannot be parametrically larger than the Planck scale. Our results are strongly suggestive of a general inconsistency in models of large-field inflation based on axions, and possibly of a more general principle forbidding super-Planckian field ranges.