New Light Species and the CMB

Title: New Light Species and the CMB

Presenter: Matthew Walters (John Hopkins U)

Chair: Viviana Niro (U Barcelona)

Abstract: I will discuss recent work done in collaboration with Christopher Brust and David E. Kaplan. Specifically, I will consider the effects of new light species on the Cosmic Microwave Background within the framework of effective field theory. These effects are parameterized in terms of the relativistic degrees of freedom present at recombination. After reviewing the relevant details of early universe thermodynamics, I will provide a map between the parameters of any particular theory and the predicted effective number of degrees of freedom. I will then use this map to interpret the recent results from the Planck satellite, presenting new constraints on the parameter space of several models containing new light species.