The suspended pinch point and SU($2$)$\times$U($1$) gauge theories

Abstract

We show that the suspended pinch point can be seen as an elliptically fibered variety with singular fibers of type I$_2$ over codimension-one points of the base and a torsionless Mordell--Weil group of rank one. In the F-theory algorithm, this corresponds to a Lie group $SU(2)\times U(1)$. We also identify the matter content as given by the direct sum of the adjoint representation (with zero U($1$)-charge) and the fundamental representation with U($1$)-charge $\pm 1$. We then study the geometry of an SU($2$)$\times$U($1$)-model given by a compact elliptically fibered variety with the singularities of a suspended pinch point. We describe in detail the crepant resolutions and the network of flops of this geometry. We compute topological invariants including the Euler characteristic and Hodge numbers. We also study the weak coupling limit of this geometry and show that it corresponds to an orientifold theory with an Sp($1$)-stack transverse to the orientifold and two brane-image-branes wrapping the orientifold.