%0 Journal Article %@ 1079-7114 %A Price, LC %A Peiris, HV %A Frazer, J %A Easther, R %D 2015 %F discovery:1467847 %I AMER PHYSICAL SOC %J Physical Review Letters %K Science & Technology, Physical Sciences, Physics, Multidisciplinary, Physics, FLUX COMPACTIFICATIONS %T Gravitational Wave Consistency Relations for Multifield Inflation %U https://discovery.ucl.ac.uk/id/eprint/1467847/ %V 114 %X 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 ∼ ∑ i λ 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 5 σ level. This gives a novel and testable prediction for the simplest multifield inflation models. %Z This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.