  Requiring a strictly local origin of visible sector phenomenology is perhaps
the strongest, most falsifiable condition that one can impose on string theory
at the high scale: it at once excludes a vast majority of the string landscape,
and yet leads naturally to constructions that can be surprisingly realistic
(and familiar). Yet only for local models can gravity be made parametrically
weak while keeping the strength of gauge- and Yukawa-couplings fixed--a limit
which is well-motivated by low-energy experiments. Conveniently, the entire
class of high-scale effective field theories that can arise from such local
models in F-theory and M-theory can be classified according to simple, purely
group-theoretic rules. In this note, we describe these rules from the viewpoint
of an effective field theorist with little interest in the underlying geometry
or high-scale physics, and we discuss the general predictions these models have
for low-energy phenomenology.
