On four-derivative terms in IIB Calabi-Yau orientifold reductions

TL;DR

This paper derives four-derivative couplings of Kähler moduli in the 4D effective supergravity from IIB Calabi-Yau orientifold reductions, including gravitational -corrections, relevant for inflation models.

Contribution

It provides the first complete derivation of four-derivative Ke4hler moduli couplings in IIB Calabi-Yau orientifold compactifications with -corrections.

Findings

Derived four-derivative couplings quadratic in Ke4hler fluctuations.

Identified couplings as friction terms in inflationary models.

Included effects of orientifold planes and gravitational -corrections.

Abstract

We perform a Kaluza-Klein reduction of IIB supergravity including purely gravitational $\alpha '^3$-corrections on a Calabi-Yau threefold, and perform the orientifold projection accounting for the presence of $O3/O7$-planes. We consider infinitesimal K\"{a}hler deformations of the Calabi-Yau background and derive the complete set of four-derivative couplings quadratic in these fluctuations coupled to gravity. In particular, we find four-derivative couplings of the K\"{a}hler moduli fields in the four-dimensional effective supergravity theory, which are referred to as friction couplings in the context of inflation.