October 15: Eirik Svanes (Oxford)
Title: Heterotic Supergravity and the alpha'-Expansion
Place: DRL 4N9
We will consider the alpha' expansion of the Strominger system derived from heterotic string compactifications to an N=1 supersymmetric effective field theory on four dimensional Minkowski space. We study the equations of motion, and show that compatibility between equations of motion and supersymmetry requires the existence of an instanton connection on the tangent bundle. A result first shown by Ivanov. Next, we discuss the alpha' expansion and show that the conformally balanced condition is required by supersymmetry and equations of motion to second order as well. We also discuss moduli, and show how the Bianchi Identity may be used to determine the higher order geometry in terms of the lower order one.