- 9/9/2018: String Dualities and an Infinity of Associative Submanifolds
- 1/10/2018: On marginal deformations of heterotic G
_{2}geometries

### September 9, 2018

TITLE: String Dualities and an Infinity of Associative Submanifolds

ABSTRACT: By applying the F-theory/heterotic/M-theory duality chain the non-perturbative superpotential in F-theory discovered by Donagi, Grassi and Witten was recently used to conjecture that a certain M-theory -manifold contains an infinite number of associative sub-manifolds, i.e. three-cycles calibrated with respect to the three-form. The corresponding M-theory superpotential derives from Euclidean M2 branes wrapping these associatives. I will prove the existence of these associative three-cycles at a certain orbifold point of the manifold, and connect the corresponding F-theroy superpotential through the M-theory/IIA/IIB/F-theory duality chain.

### January 10, 2018

TITLE: On marginal deformations of heterotic G_{2} geometries

ABSTRACT: A seven dimensional supersymmetric heterotic string compactification is a structure manifold Y equipped with an instanton bundle , for which the geometry and bundle satisfy several coupled differential constraints. Ignoring higher curvature corrections, this includes holonomy manifolds with instanton bundles, but can also be more generic. Recently, the infinitesimal moduli of such compactifications was derived and identified with the first cohomology of a particular differential complex. I will review this result, and proceed to re-derive it from the two-dimensional sigma model point of view, whose target space is the above mentioned heterotic geometry. In particular, I will identify the worldsheet BRST operator whose cohomology is isomorphic to the infinitesimal deformations of the geometry. I will explain new concepts as they are introduced, in an effort to make the talk accessible to non-experts.