HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

Degenerate higher derivative theories beyond Horndeski: evading the Ostrogradski instability

Abstract : Theories with higher order time derivatives generically suffer from ghost-like instabilities, known as Ostrogradski instabilities. This fate can be avoided by considering ``degenerate'' Lagrangians, whose kinetic matrix cannot be inverted, thus leading to constraints between canonical variables and a reduced number of physical degrees of freedom. In this work, we derive in a systematic way the degeneracy conditions for scalar-tensor theories that depend quadratically on second order derivatives of a scalar field. We thus obtain a classification of all degenerate theories within this class of scalar-tensor theories. The quartic Horndeski Lagrangian and its extension beyond Horndeski belong to these degenerate cases. We also identify new families of scalar-tensor theories with the property that they are degenerate despite the nondegeneracy of the purely scalar part of their Lagrangian.
Complete list of metadata

https://hal.archives-ouvertes.fr/hal-01554319
Contributor : Inspire Hep Connect in order to contact the contributor
Submitted on : Monday, July 3, 2017 - 5:50:25 PM
Last modification on : Thursday, April 7, 2022 - 1:58:23 PM

Links full text

Identifiers

Collections

Citation

David Langlois, Karim Noui. Degenerate higher derivative theories beyond Horndeski: evading the Ostrogradski instability. JCAP, 2016, 02, pp.034. ⟨10.1088/1475-7516/2016/02/034⟩. ⟨hal-01554319⟩

Share

Metrics

Record views

107