String loop corrections to the universal hypermultiplet

TL;DR

This paper investigates one-loop quantum corrections to the universal hypermultiplet in type IIA string theory compactified on Calabi-Yau threefolds, revealing non-trivial modifications to the metric and field identities.

Contribution

It demonstrates that one-loop corrections depend on the Calabi-Yau Euler number and alter the hypermultiplet's quaternionic metric, which is no longer Kahler, providing new insights into string compactification effects.

Findings

One-loop corrections are proportional to the Calabi-Yau Euler number.

The corrected metric is non-Kahler.

Loop effects renormalize the Calabi-Yau volume and modify Bianchi identities.

Abstract

We study loop corrections to the universal dilaton supermultiplet for type IIA strings compactified on Calabi-Yau threefolds. We show that the corresponding quaternionic kinetic terms receive non-trivial one-loop contributions proportional to the Euler number of the Calabi-Yau manifold, while the higher-loop corrections can be absorbed by field redefinitions. The corrected metric is no longer Kahler. Our analysis implies in particular that the Calabi-Yau volume is renormalized by loop effects which are present even in higher orders, while there are also one-loop corrections to the Bianchi identities for the NS and RR field strengths.