Inflationary implications of the Covariant Entropy Bound and the Swampland de Sitter Conjectures

Abstract: We present a proposal to relate the de Sitter Conjecture (dSC) to the Covariant Entropy Bound (CEB). By assuming an early phase of accelerated expansion where the CEB is satisfied, we take into account a contribution from extra-dimensions to the four-dimensional entropy which restricts the values of the usual slow-roll parameters. We show in this context that the dSC inequalities follow from the CEB -- including their mutual exclusion -- in both single and multi-field inflationary scenarios. We also observe that the order one constants, c and c' in the conjecture are given in terms of physical quantities such as the change in entropy over time, the Hubble constant and the dynamics of the effective scalar fields. Finally, we give a simple example to illustrate a possible contribution to the four-dimensional entropy from a flux string scenario.