Cosmological limits on axions and axion-like particles
arXiv:1210.3196
Abstract
The axion is a pseudo-Nambu-Goldstone boson. It appears after the spontaneous breaking of the Peccei-Quinn symmetry, which was proposed to solve the strong-CP problem. Other pseudo-Nambu-Goldstone bosons, postulated in some extensions of the standard model of particle physics, are called axion-like particles (ALPs) if they share certain characteristics with the axion, in particular a coupling to two photons. Thus far, axion and ALP searches have been unsuccessful, indicating that their couplings have to be extremely weak. However, axions and ALPs could be responsible for some observable effects in astrophysics and cosmology, which can also be exploited to constrain the parameter space of these particles. We focus on limits coming from cosmology, which is an optimal field for studying axions and ALPs. In particular, we first investigate the possibility of a primordial population of axions and ALPs arising during the earliest epochs of the universe. The importance of this analysis lies on the fact that axions and ALPs are ideal dark matter candidates because of their faint interactions and their peculiar production mechanisms. Finally, we consider the consequences of the decay of such a population on specific cosmological observables, namely the photon spectrum of galaxies, the cosmic microwave background, the effective number of neutrino species, and the abundance of primordial elements. Our bounds constitute the most stringent probes of early decays and exclude a part of the ALP parameter space that is otherwise very difficult to test experimentally.
132 pages, 32 figures, PhD Thesis
References in corpus (23)
- An Improved Experimental Limit on the Electric Dipole Moment of the Neutron
- Bose-Einstein Condensation of Dark Matter Axions
- A Bitter Pill: The Primordial Lithium Problem Worsens
- Evidence for a new light spin-zero boson from cosmological gamma-ray propagation?
- New PVLAS results and limits on magnetically induced optical rotation and ellipticity in vacuum
- Cosmology seeking friendship with sterile neutrinos
- New limits on the density of the extragalactic background light in the optical to the far-infrared from the spectra of all known TeV blazars
- The Milky Way as a Kiloparsec-Scale Axionscope
- Where to find a dark matter sterile neutrino?
- A robust upper limit on N_eff from BBN, circa 2011
- Deuterium Abundance in the Most Metal-Poor Damped Lyman alpha System: Converging on Omega_baryons
- Axions and the cooling of white dwarf stars
- Helioscope Bounds on Hidden Sector Photons
- Detecting Axion-Like Particles With Gamma Ray Telescopes
- Thermal axion production in the primordial quark-gluon plasma
- A Telescope Search for Decaying Relic Axions
- Astrophysical Effects of Scalar Dark Matter Miniclusters
- Robust Cosmological Bounds on Neutrinos and their Combination with Oscillation Results
- Effects of Axion-Photon Mixing on Gamma-Ray Spectra from Magnetized Astrophysical Sources
- The Caustic Ring Model of the Milky Way Halo
- Primordial magnetic field limits from cosmological data
- Physics of Cosmic Reionization
- Cavity Microwave Searches for Cosmological Axions