A Tale of Two $U(1)$'s: Kinetic Mixing from Lattice WGC States

TL;DR

This paper demonstrates that the Lattice Weak Gravity Conjecture implies non-zero kinetic mixing between Abelian gauge groups, supported by string theory and field theory analyses, with implications for phenomenology.

Contribution

It establishes a connection between the Lattice Weak Gravity Conjecture and kinetic mixing, providing quantitative estimates from string and field theory models.

Findings

Kinetic mixing is generically non-zero under WGC conditions.

Quantitative estimates of kinetic mixing from string theory models.

Analysis of field theory compactifications supports the conjecture.

Abstract

We point out that the states required by the Lattice Weak Gravity Conjecture, along with certain genericity conditions, imply the existence of non-vanishing kinetic mixing between massless Abelian gauge groups in the low-energy effective theory. We carry out a phenomenological estimate using a string-inspired probability distribution for the masses of superextremal states and compare the results to expectations from string theory and field theory, estimating the magnitude of kinetic mixing in each case. In the string case, we compute the kinetic mixing in an ensemble of 1858 MSSM-like heterotic orbifolds as well as in Type II supergravity on a Calabi-Yau manifold. From the field theory perspective, we consider compactifications of a 5D gauge theory. Finally, we discuss potential loopholes that can evade the bounds set by our estimates.