79 citations · 197 across the 6 of their papers we have counts for
6 papers
A No-go Theorem for a Gauge Vector as a Space-time Goldstone
Remko Klein, Emanuel Malek, Diederik Roest +1
Scalars and fermions can arise as Goldstone modes of non-linearly realised extensions of the Poincare group (with important implications for the soft limits of such theories): the…
Symmetry Breaking Patterns for Inflation
Remko Klein, Diederik Roest, David Stefanyszyn
We study inflationary models where the kinetic sector of the theory has a non-linearly realised symmetry which is broken by the inflationary potential. We distinguish between kinet…
Spontaneously Broken Spacetime Symmetries and the Role of Inessential Goldstones
Remko Klein, Diederik Roest, David Stefanyszyn
In contrast to internal symmetries, there is no general proof that the coset construction for spontaneously broken spacetime symmetries leads to universal dynamics. One key differe…
Higher Derivative Field Theories: Degeneracy Conditions and Classes
Marco Crisostomi, Remko Klein, Diederik Roest
We provide a full analysis of ghost free higher derivative field theories with coupled degrees of freedom. Assuming the absence of gauge symmetries, we derive the degeneracy condit…
Exorcising the Ostrogradsky ghost in coupled systems
Remko Klein, Diederik Roest
The Ostrogradsky theorem implies that higher-derivative terms of a single mechanical variable are either trivial or lead to additional, ghost-like degrees of freedom. In this lette…
Galileons as the Scalar Analogue of General Relativity
Remko Klein, Mehmet Ozkan, Diederik Roest
We establish a correspondence between general relativity with diffeomorphism invariance and scalar field theories with Galilean invariance: notions such as the Levi-Civita connecti…