New Exceptional EFTs in de Sitter Space from Generalised Energy Conservation

TL;DR

This paper uncovers a link between exceptional EFTs in de Sitter space and a generalized energy conservation principle, constraining theories and revealing new fixed-interaction models.

Contribution

It introduces a novel connection between GEC and exceptional EFTs in de Sitter, leading to the rediscovery of known theories and the prediction of new fixed-interaction models.

Findings

Rediscovery of DBI and Galileon theories

Evidence for new exceptional theories at higher conformal dimensions

Proposal that each integer conformal dimension ≥ 4 has a fixed EFT

Abstract

We discover a surprising relationship between exceptional effective field theories (EFTs) in de Sitter space and a notion of \textit{generalised energy conservation} (GEC) of an S-matrix defined in an extended Poincar\'{e} patch of four-dimensional de Sitter. By demanding that such an S-matrix only has support when the total energies of in and out states are equal, we constrain the coupling constants in theories of self-interacting scalars living in the exceptional series of de Sitter representations. We rediscover the theories of Dirac-Born-Infeld (DBI) and Special Galileon, and when increasing the conformal dimension we find evidence for new exceptional theories where the four-point scalar self interactions are uniquely fixed in terms of a single coupling constant. We conjecture that for each integer conformal dimension $\Delta \geq 4$, there is at least one exceptional EFT that can be entirely fixed by GEC.