On the Sen limit squared

TL;DR

This paper introduces a new class of F-theory vacua as a specialization of $E_6$ fibrations and constructs a 'square' of the Sen limit, revealing potential new insights into orientifold theories and tadpole relations.

Contribution

It presents a novel weak coupling limit related to $E_6$ fibrations, extending the concept of the Sen limit and exploring its implications for orientifold theories.

Findings

The constructed limit can be viewed as the 'square' of the Sen limit.

The tadpole relation suggests a connection to oriented theories on the base.

The work provides a new perspective on F-theory vacua and their weak coupling limits.

Abstract

We introduce a class of F-theory vacua which may be viewed as a specialization of the so-called $E_6$ fibration, and construct a weak coupling limit associated with such vacua which we view as the `square' of the Sen limit. We find that while Sen's limit is naturally viewed as an orientifold theory, the universal tadpole relation which equates the D3 charge between the associated F-theory compactification and the limit we construct suggests that perhaps the limiting theory is in fact an oriented theory compactified on the base of the F-theory elliptic fibration.