Observable gravitational waves from inflation with small field excursions

摘要: The detection of primordial gravitational waves, or tensor perturbations, would be regarded as compelling evidence for inflation. canonical measure this is the ratio to scalar r. For single-field slow-roll models inflation with small field excursions, Lyth bound dictates that if evolution parameter epsilon monotonic, tensor-to-scalar must below observationally detectable levels. We describe how non-monotonic can evade and generate large r, even excursions. This has consequences power spectrum it necessarily predicts an enhancement in at very scales significant scale-dependent running CMB scales. effect not been appropriately accounted previous analyses. a mechanism will generically produce required behaviour give example arising well-motivated small-field model. model r\geq0.05 while satisfying all current observational constraints.