Daniel BaumannGreen, DanielDanielGreen2024-02-222024-02-222012-05-011475-7516https://scholars.lib.ntu.edu.tw/handle/123456789/639846We explore the consequences of a detection of primordial tensor fluctuations for general single-field models of inflation. Using the effective theory of inflation, we propose a generalization of the Lyth bound that applies to models of inflation coupled to Einstein gravity. Our strongest bound applies to all single-field models with two-derivative kinetic terms for the scalar fluctuations and is always stronger than the corresponding bound for slow-roll models. This shows that non-trivial dynamics of the inflaton can't evade the Lyth bound. We also present a weaker, but more universal bound that holds when the Null Energy Condition (NEC) is satisfied at horizon crossing. © 2012 IOP Publishing Ltd and Sissa Medialab srl.gravitational waves and CMBR polarization | inflationjournal article10.1088/1475-7516/2012/05/0172-s2.0-84861809531https://api.elsevier.com/content/abstract/scopus_id/84861809531