New Orientifold Weak Coupling Limits in F-theory

TL;DR

This paper introduces new explicit weak coupling limits in F-theory, expanding the range of supersymmetric configurations and providing a geometric framework that generalizes Sen's original construction.

Contribution

It develops novel constructions of F-theory weak coupling limits beyond Weierstrass forms, enabling new brane configurations and simplifying the geometric interpretation.

Findings

New explicit weak coupling limits for non-Weierstrass elliptic fibrations

Enlarged set of supersymmetric F-theory configurations

Explicit examples for E8, E7, and E6 fibrations

Abstract

We present new explicit constructions of weak coupling limits of F-theory generalizing Sen's construction to elliptic fibrations which are not necessary given in a Weierstrass form. These new constructions allow for an elegant derivation of several brane configurations that do not occur within the original framework of Sen's limit, or which would require complicated geometric tuning or break supersymmetry. Our approach is streamlined by first deriving a simple geometric interpretation of Sen's weak coupling limit. This leads to a natural way of organizing all such limits in terms of transitions from semistable to unstable singular fibers. These constructions provide a new playground for model builders as they enlarge the number of supersymmetric configurations that can be constructed in F-theory. We present several explicit examples for E8, E7 and E6 elliptic fibrations.