title: Gravitational wave consistency relations for multifield inflation.
abstract: We study the tensor spectral index n(t) and the tensor-to-scalar ratio r in the simplest multifield extension to single-field, slow-roll inflation models. We show that multifield models with potentials V∼[under ∑]iλ_{i}|ϕ_{i}|^{p} have different predictions for n(t)/r than single-field models, even when all the couplings are equal λ_{i}=λ_{j}, due to the probabilistic nature of the fields' initial values. We analyze well-motivated prior probabilities for the λ_{i} and initial conditions to make detailed predictions for the marginalized probability distribution of n(t)/r. With O(100) fields and p>3/4, we find that n(t)/r differs from the single-field result of n(t)/r=-1/8 at the 5σ level. This gives a novel and testable prediction for the simplest multifield inflation models.
authors: Department of Physics, University of Auckland, Private Bag 92019 Auckland, New Zealand.
authors: Layne C
authors: LC
authors: Price
authors: Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
authors: Hiranya V
authors: HV
authors: Peiris
authors: Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48040 Bilbao, Spain.
authors: Jonathan
authors: J
authors: Frazer
authors: Department of Physics, University of Auckland, Private Bag 92019 Auckland, New Zealand.
authors: Richard
authors: R
authors: Easther