Geometric interpretation of the large image index Original Research Article

We study WZW models with the large image superconformal symmetry. Our main result is a geometric interpretation of the large image index. In particular, we find that states contributing to the index belong to spectral flow orbits of special RR ground states. We use (anti-)holomorphic differentials with torsion to clarify the geometric meaning of these states in terms of differential forms on the target space.