TY - JOUR
T1 - Restricted Galileons
AU - Berezhiani, Lasha
AU - Chkareuli, Giga
AU - Gabadadze, Gregory
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/12/9
Y1 - 2013/12/9
N2 - We study Galileon theories that emerge in ghost-free massive gravity. In particular, we focus on a subclass of these theories where the Galileons can be completely decoupled from the tensor Lagrangian. These Galileons differ from generic ones - they have interrelated coefficients of the cubic and quartic terms, and most importantly, a nonstandard coupling to external stress-tensors, governed by the same coefficient. We show that this theory has no static stable spherically symmetric solutions that would interpolate from the Vainshtein region to flat space; these two regions cannot be smoothly matched for the sign of the coefficient for which fluctuations are stable. Instead, for this sign choice, a solution in the Vainshtein domain is matched onto a cosmological background. Small fluctuations above this solution are stable, and sub-luminal. We discuss observational constraints on this theory, within the quantum effective Lagrangian approach, and argue that having a graviton mass of the order of the present-day Hubble parameter, is consistent with the data. Last but not least, we also present a general class of cosmological solutions in this theory, some of which exhibit the demixing phenomenon, previously found for the self-accelerated solution.
AB - We study Galileon theories that emerge in ghost-free massive gravity. In particular, we focus on a subclass of these theories where the Galileons can be completely decoupled from the tensor Lagrangian. These Galileons differ from generic ones - they have interrelated coefficients of the cubic and quartic terms, and most importantly, a nonstandard coupling to external stress-tensors, governed by the same coefficient. We show that this theory has no static stable spherically symmetric solutions that would interpolate from the Vainshtein region to flat space; these two regions cannot be smoothly matched for the sign of the coefficient for which fluctuations are stable. Instead, for this sign choice, a solution in the Vainshtein domain is matched onto a cosmological background. Small fluctuations above this solution are stable, and sub-luminal. We discuss observational constraints on this theory, within the quantum effective Lagrangian approach, and argue that having a graviton mass of the order of the present-day Hubble parameter, is consistent with the data. Last but not least, we also present a general class of cosmological solutions in this theory, some of which exhibit the demixing phenomenon, previously found for the self-accelerated solution.
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U2 - 10.1103/PhysRevD.88.124020
DO - 10.1103/PhysRevD.88.124020
M3 - Article
AN - SCOPUS:84890957858
VL - 88
JO - Physical Review D - Particles, Fields, Gravitation and Cosmology
JF - Physical Review D - Particles, Fields, Gravitation and Cosmology
SN - 1550-7998
IS - 12
M1 - 124020
ER -