Stability and Superluminality of Spherical DBI Galileon Solutions

The Dirac-Born-Infeld (DBI) Galileons are a generalization of the Galileon terms, which extend the internal Galilean symmetry to an internal relativistic symmetry, and can also be thought of as generalizations of DBI which yield second order field equations. We show that, when considered as local modifications to gravity, such as in the Solar System, there exists a region of parameter space in which spherically symmetric static solutions exist and are stable. However, these solutions always exhibit superluminality, casting doubt on the existence of a standard Lorentz invariant UV completion. Disciplines Physical Sciences and Mathematics | Physics Comments Suggested Citation: G.L. Goon, K. Hinterbichler, M. Trodden. (2011). Stability and superluminality of spherical DBI Galileon solutions. Physical Review D 83, 085015. © 2011 The American Physical Society http://dx.doi.org/10.1103/PhysRevD.83.085015 This journal article is available at ScholarlyCommons: http://repository.upenn.edu/physics_papers/157 Stability and superluminality of spherical DBI Galileon solutions Garrett L. Goon,* Kurt Hinterbichler, and Mark Trodden Center for Particle Cosmology, Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA (Received 20 September 2010; published 12 April 2011) The Dirac-Born-Infeld (DBI) Galileons are a generalization of the Galileon terms, which extend the internal Galilean symmetry to an internal relativistic symmetry, and can also be thought of as generalizations of DBI which yield second order field equations. We show that, when considered as local modifications to gravity, such as in the Solar System, there exists a region of parameter space in which spherically symmetric static solutions exist and are stable. However, these solutions always exhibit superluminality, casting doubt on the existence of a standard Lorentz invariant UV completion. DOI: 10.1103/PhysRevD.83.085015 PACS numbers: 98.80. k, 04.50. h, 04.50.Kd