Orbifold string topology

Orbifold SUSY GUT from the Heterotic String

From the string partition function, we discuss the mass-shell and GSO projection conditions valid for KaluzaKlein (KK) as well as massless states in the heterotic string theory compactified on a nonprime orbifold. Using the obtained conditions we construct a 4D string standard model, which is embedded in a 6D SUSY GUT by including KK states above the compactification scale. We discuss the strin...

Unification in Quasi–Realistic Orbifold String GUTs

E6 grand unification combines the Standard Model matter and Higgs states in the single 27 representation. I discuss how the E6 structure underlies the quasi–realistic free fermion heterotic–string models. E6 → SO(10) × U(1) breaking is obtained by a GSO phase in the N = 1 partition function. The equivalence of this symmetry breaking phase with a particular choice of a boundary condition basis v...

String topology for stacks

We establish the general machinery of string topology for differentiable stacks. This machinery allows us to treat on an equal footing free loops in stacks and hidden loops. In particular, we give a good notion of a free loop stack, and of a mapping stack Map(Y,X), where Y is a compact space and X a topological stack, which is functorial both in X and Y and behaves well enough with respect to p...

Higher String Topology Operations

In [1] Chas and Sullivan have defined an intersection-type product on the homology of the free loop space LM of an oriented manifold M. In this paper we show how to extend this construction to a topological conformal field theory of degree d. In particular, we get operations on H∗LM which are parameterized by the homology of the moduli space of open-closed Riemann surfaces.

Notes on String Topology