TY - JOUR AB - We study the development of caustics in shift-symmetric scalar field theories by focusing on simple waves with an SO(p)-symmetry in an arbitrary number of space dimensions. We show that the pure Galileon, the DBI–Galileon, and the extreme-relativistic Galileon naturally emerge as the unique set of caustic-free theories, highlighting a link between the caustic-free condition for simple SO(p)-waves and the existence of either a global Galilean symmetry or a global (extreme-)relativistic Galilean symmetry. AU - de,Rham C AU - Motohashi,H DO - 10.1103/PhysRevD.95.064008 PY - 2017/// SN - 1550-2368 TI - Caustics for spherical waves T2 - Physical Review D - Particles, Fields, Gravitation and Cosmology UR - http://dx.doi.org/10.1103/PhysRevD.95.064008 UR - http://hdl.handle.net/10044/1/51625 VL - 95 ER -