Perturbative reduction of derivative order in EFT

• Published in: The journal of high energy physics Vol. 2018; no. 2; pp. 1 - 36
• Main Author: Glavan, Dražen
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2018; Springer Nature B.V; SpringerOpen
• Subjects: Classical and Quantum Gravitation; Classical Theories of Gravity; Cosmology of Theories beyond the SM; Degrees of freedom; Effective Field Theories; Elementary Particles; Field theory; High energy physics; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; String Theory; Classical Theories of Gravity; Effective Field Theories; Cosmology of Theories beyond the SM
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP02(2018)136

A bstract Higher derivative corrections are ubiquitous in effective field theories, which seemingly introduces new degrees of freedom at successive orders. This is actually an artefact of the implicit local derivative expansion defining effective field theories. We argue that higher derivative corrections that introduce additional degrees of freedom should be removed and their effects captured either by lower derivative corrections, or special combinations of higher derivative corrections not propagating extra degrees of freedom. Three methods adapted for this task are examined and field redefinitions are found to be most appropriate. First order higher derivative corrections in a scalar tensor theory are removed by field redefinition and it is found that their effects are captured by a subset of Horndeski theories. A case is made for restricting the effective field theory expansions in principle to only terms not introducing additional degrees of freedom.