Evolution of perturbation and power spectrum in a two-component ultralight axionic universe

Abstract

Evolution of cosmic perturbations in two-component ultralight axionic universes is investigated. We present the first spectral computation of perturbations in multi-component universes. A particular case composed of light extreme axions and free massive particles offers a possibility for the formation of very high-redshift massive galaxies, which are normally required to host massive early quasars. Our computation retains the information of perturbed velocities for individual axion components, an information that opens a new avenue for setting up initial conditions for future axion dark matter simulations.

Polarization and Correlation Effects in Lepton Flavor Violated Decays Induced by Axion-Like Particle

“…In case of that 2m e < m a < m µ , flavor diagonal contributions have to be dominant in order to account for these two anomalies simultaneously, and the ALP couplings to electron should be larger than the ALP couplings to muon with opposite sign [43]. If the ALP is ultra light, flavor-violating ALP couplings can never give correct contributions to the anomalies, and hence can put strong limits on the corresponding couplings [47][48][49][50][51][52][53][54]. In this case, flavor violated decay modes τ → a can provide direct measurement on the relevant flavor violation parameters.…”