Primordial gravitational waves in Horndeski gravity

@article{Nunes2019PrimordialGW,
  title={Primordial gravitational waves in Horndeski gravity},
  author={Rafael C. Nunes and M{\'a}rcio E. S. Alves and Jose C.N. de Araujo},
  journal={Physical Review D},
  year={2019}
}
We investigate the propagation of primordial gravitational waves within the context of the Horndeski theories, for this, we present a generalized transfer function quantifying the sub-horizon evolution of gravitational waves modes after they enter the horizon. We compare the theoretical prediction of the modified primordial gravitational waves spectral density with the aLIGO, Einstein telescope, LISA, gLISA and DECIGO sensitivity curves. Assuming reasonable and different values for the free… 

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