Conservation of the nonlinear curvature perturbation in generic single-field inflation

Atsushi Naruko, Misao Sasaki

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


It is known that the curvature perturbation on uniform energy density (or comoving or uniform Hubble) slices on superhorizon scales is conserved to full nonlinear order if the pressure is only a function of the energy density (i.e. if the perturbation is purely adiabatic), independent of the gravitational theory. Here, we explicitly show that the same conservation holds for a universe dominated by a single scalar field provided that the field is in an attractor regime, for a very general class of scalar-field theories. However, we also show that if the scalar-field equation contains a second time derivative of the metric, as in the case of the Galileon (or kinetic braiding) theory, one has to invoke the gravitational-field equations to show the conservation.

Original languageEnglish
Article number072001
JournalClassical and Quantum Gravity
Issue number7
Publication statusPublished - 2011 Apr 7

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


Dive into the research topics of 'Conservation of the nonlinear curvature perturbation in generic single-field inflation'. Together they form a unique fingerprint.

Cite this