On Global Embedding of Assisted Fibre Inflation

TL;DR

This paper explores embedding fibre inflation models in string theory, focusing on sharing the inflationary field range among multiple moduli to overcome geometric constraints.

Contribution

It proposes a multi-field assistance mechanism to achieve successful inflation within the Kähler cone bounds in string compactifications.

Findings

Multiple fibre moduli can share the trans-Planckian field range.

Assisted inflation can occur before hitting Kähler cone boundaries.

The approach helps realize sufficient e-folds in string-inspired models.

Abstract

Fibre inflation is one of the most attractive models realized in the type IIB orientifold compactification. It is embedded in the framework of L(arge) V(olume) S(cenarios) using a class of compactifying Calabi-Yau (CY) threefolds having K3-fibration. The standard single-field fibre inflation is driven by a fibre modulus which needs to travel a trans-Planckian distance of the order of ${\cal O}(5-8)$M$_p$ in the effective moduli space. The global embedding attempts using concrete CY orientifold setups have shown that K\"ahler cone conditions can generically induce some significantly tight bounds on the inflaton range, especially in the presence of a Swiss-Cheese structure via an exceptional rigid divisor in the CY threefold. Such field range bounds usually obstruct the inflationary plateau, leading to insufficient number of efolds during the inflationary dynamics. In this context, we review our recent work about the possibility of assisting multiple fibre moduli such that the burden of traveling the required trans-Planckian distance could be shared by multiple fields, and successful inflation could be realized before hitting (or being too close to) their respective individual K\"ahler cone boundaries.