Large Blue Spectral Index from a Conformal Limit of a Rotating Complex Scalar

CDM isocurvature power with large blue spectral index can explain the 2-sigma hint in Planck data and recent JWST observation of high redshift galaxies. A well-known method for generating a large blue spectral index for axionic isocurvature perturbations involves a flat direction without a quartic potential term for the axion field’s radial partner. In this talk, we discuss how a large blue spectral index can be achieved even with a quartic potential term linked to the Peccei-Quinn symmetry breaking radial partner. We utilize the fact that a large radial direction with a quartic term can naturally induce a “conformal limit”, producing an isocurvature spectral index of 3. Alternatively, this limit can be seen as the angular momentum of the initial conditions slowing the radial field or as a superfluid limit. The large angular momentum necessitates a careful quantisation process to establish the vacuum state. We outline the parametric region that aligns with axion dark matter and isocurvature cosmology, and discuss prospects for future detection.