de Sitter swampland bound in the Dirac-Born-Infeld inflation model
  We study the de Sitter (dS) swampland conjecture in the Dirac-Born-Infeld
(DBI) inflation model. We obtain the dS swampland bound for the relativistic
regime using Bousso's entropy bound argument and proper distance. It restricts
$m_{\rm Pl}\nabla V/V$ by some positive constant depending on warping and the
field range. In the specific case of the DBI model driven by the quadratic
potential, the model-dependent backreaction argument is interpreted as a
natural bound for the slow-roll parameter. This shows that quasi-dS spacetime
in the DBI model is a result of tuning.
