The paper discusses the implications of the BICEP2 Collaboration's findings on the ratio of power in tensor to scalar density perturbations in the CMB, which provides evidence for Inflation at the GUT scale. It explores alternative sources for the signal, such as a self-ordering scalar field transition, and the conditions under which these alternatives could be ruled out. The authors argue that improved limits on isocurvature contributions could confirm Inflation as the primary source of the observed signal.
documents/EFTA00615287.pdf
{}