Dark radiation and decaying matter

  • M.C. Gonzalez-Garcia
  • V. Niro
  • Jordi Salvado


Recent cosmological measurements favour additional relativistic energy density beyond the one provided by the three active neutrinos and photons of the Standard Model (SM). This is often referred to as “dark radiation”, suggesting the need of new light states in the theory beyond those of the SM. In this paper, we study and numerically explore the alternative possibility that this increase comes from the decay of some new form of heavy matter into the SM neutrinos. We study the constraints on the decaying matter density and its lifetime, using data from the Wilkinson Microwave Anisotropy Probe, the South Pole Telescope, measurements of the Hubble constant at present time, the results from high-redshift Type-I supernovae and the information on the Baryon Acoustic Oscillation scale. We, moreover, include in our analysis the information on the presence of additional contributions to the expansion rate of the Universe at the time of Big Bang Nucleosynthesis. We compare the results obtained in this decaying matter scenario with those obtained withthe standard analysis in terms of a constant N eff.


Cosmology of Theories beyond the SM Neutrino Physics 


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Copyright information

© SISSA, Trieste, Italy 2013

Authors and Affiliations

  1. 1.Institució Catalana de Recerca i Estudis Avançats (ICREA), Departament d’Estructura i Constituents de la Matèria and Institut de Ciencies del CosmosUniversitat de BarcelonaBarcelonaSpain
  2. 2.C.N. Yang Institute for Theoretical PhysicsState University of New York at Stony BrookStony BrookU.S.A.
  3. 3.Departament d’Estructura i Constituents de la Matèria and Institut de Ciencies del CosmosUniversitat de BarcelonaBarcelonaSpain
  4. 4.Wisconsin IceCube Particle Astrophysics Center (WIPAC) and Department of PhysicsUniversity of WisconsinMadisonU.S.A.

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