Fluxbranes: Moduli Stabilisation and Inflation
Arthur Hebecker, Sebastian C. Kraus, Moritz Kuntzler, Dieter Lust, Timo Weigand
TL;DR
Fluxbrane inflation is analyzed as a stringy D-term hybrid inflation realized in a hierarchical Large Volume Scenario (LVS). By introducing at least four Kähler moduli, with three large cycles, the authors achieve moduli stabilisation compatible with inflation and suppress cosmic strings, while addressing consistency concerns about FI terms. They provide both parametric scaling relations and a detailed numerical example showing a Minkowski/de Sitter minimum and viable D3-tadpole, albeit with the η-problem remaining a challenge for future refinements. Overall, the work demonstrates the viability of a string-derived D-term inflation mechanism in a hierarchical LVS framework and outlines concrete directions for achieving a fully controlled, explicit realization.
Abstract
Fluxbrane inflation is a stringy version of D-term inflation in which two fluxed D7-branes move towards each other until their (relative) gauge flux annihilates. Compared to brane-antibrane inflation, the leading-order inflationary potential of this scenario is much flatter. In the present paper we first discuss a new explicit moduli stabilisation procedure combining the F- and D-term scalar potentials: It is based on fluxed D7-branes in a geometry with three large four-cycles of hierarchically different volumes. Subsequently, we combine this moduli stabilisation with the fluxbrane inflation idea, demonstrating in particular that CMB data (including cosmic string constraints) can be explained within our setup of hierarchical large volume CY compactifications. We also indicate how the eta-problem is expected to re-emerge through higher-order corrections and how it might be overcome by further refinements of our model. Finally, we explain why recently raised concerns about constant FI terms do not affect the consistent, string-derived variant of D-term inflation discussed in this paper.