| A Microscopic Limit on Gravitational Waves from D-brane Inflation (2006) | |||||||||
Abstract | |||||||||
| We derive a microscopic bound on the maximal field variation of the inflaton during warped D-brane inflation. By a result of Lyth, this implies an upper limit on the amount of gravitational waves produced during inflation. We show that a detection at the level $r > 0.01$ would falsify slow roll D-brane inflation. In DBI inflation, detectable tensors may be possible in special compactifications, provided that $r$ decreases rapidly during inflation. We also show that for the special case of DBI inflation with a quadratic potential, current observational constraints imply strong upper bounds on the five-form flux.. Comment: 8 pages | |||||||||
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