Gravitational Wave Decay into Dark Energy

Paolo Creminelli; Matthew Lewandowski; Giovanni Tambalo; Filippo Vernizzi

doi:10.1088/1475-7516/2018/12/025

paper

Gravitational Wave Decay into Dark Energy

arXiv:1809.03484 · doi:10.1088/1475-7516/2018/12/025

Abstract

We study the decay of gravitational waves into dark energy fluctuations $π$ , through the processes $γ \to π π$ and $γ \to γ π$ , made possible by the spontaneous breaking of Lorentz invariance. Within the EFT of Dark Energy (or Horndeski/beyond Horndeski theories) the first process is large for the operator $\frac{1}{2} m ~_{4}^{2} (t) δ g^{00} (^{(3)} R + δ K_{μ}^{ν} δ K_{ν}^{μ} - δ K^{2})$ , so that the recent observations force $m ~_{4} = 0$ (or equivalently $α_{H} = 0$ ). This constraint, together with the requirement that gravitational waves travel at the speed of light, rules out all quartic and quintic GLPV theories. Additionally, we study how the same couplings affect the propagation of gravitons at loop order. The operator proportional to $m ~_{4}^{2}$ generates a calculable, non-Lorentz invariant higher-derivative correction to the graviton propagation. The modification of the dispersion relation provides a bound on $m ~_{4}^{2}$ comparable to the one of the decay. Conversely, operators up to cubic Horndeski do not generate sizeable higher-derivative corrections.

arXiv comment24 pages. Added references. Matches JCAP version

Gravitational Wave Decay into Dark Energy

Abstract

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