Thermal unparticles: A new form of energy density in the universe
Journal
European Physical Journal C
Journal Volume
60
Journal Issue
2
Pages
317-321
Date Issued
2009
Author(s)
Abstract
An unparticle U with scaling dimension dy has peculiar thermal properties due to its unique phase space structure. We find that the equation of state parameter ωu, the ratio of pressure to energy density, is given by 1/(2du + 1), providing a new form of energy in our universe. In an expanding universe, the unparticle energy density ρu(T) evolves dramatically differently from that for photons. For du > 1, even if ρu(TD) at a high decoupling temperature TD is very small, it is possible to have a large relic density ρu(Tγ) at present photon temperature T0, large enough to play the role of dark matter. We calculate TD and ρu(Tγ) using photon-unparticle interactions for illustration. © Springer-Verlag/Società Italiana di Fisica 2009.
Type
journal article