# High Energy Theory Seminar: "Matter Transitions and Heterotic/F-theory duality"

We explore a novel type of transition in certain 6D and 4D Heterotic/F-theory dual pairs, in which the matter content of the theory changes while the gauge group and other parts of the spectrum remain invariant. Such transitions can occur, for example, for SU(6), SU(7), and SU(8) gauge groups, where matter in a three-index antisymmetric representation is exchanged in the transition for matter in a two-index antisymmetric representation. These matter transitions are realized by passing through superconformal theories at the transition point. We also briefly describe some other situations, with groups such as Sp(3), SO(12), and SU(3), where analogous matter transitions can occur between different representations. For SU(3), in particular, we find a matter transition between adjoint matter and matter in the symmetric representation, giving an explicit Weierstrass model for the F-theory description of the symmetric representation that complements other recent analogous constructions.