Informal Pizza Seminar

Topology from Cosmology

Vijay Balasubramanian

University of Pennsylvania

We show that cosmological observables can constrain the topology of the compact additional dimensions predicted by string theory. To do this, we develop a general strategy for relating CMB observables to the microscopic parameters of the potentials and field-dependent kinetic terms of the multiple scalar fields that arise in the low- energy limit of string theory. We apply this formalism to the Large Volume Scenarios in Type IIB flux compactifications where analytical calculations are possible. As an example we consider a case with two scalar fields and demonstrate that that a small variation in the Euler number of the compact hidden dimensions can lead to a large variation in the spectral index. Our methods generalize to other settings.