Is the CMB telling us that dark matter is weaker than weakly interacting?

Abstract

If moduli, or other long-lived heavy states, decay in the early universe in part into light and feebly interacting particles (such as axions), these decay products could account for the additional energy density in radiation that is suggested by recent measurements of the CMB. These moduli decays will also, however, alter the expansion history of the early universe, potentially diluting the thermal relic abundance of dark matter. If this is the case, then dark matter particles must annihilate with an even lower cross section than required in the standard thermal scenario (sigma v < 3x10^-26 cm^3/s) if they are to make up the observed density of dark matter. This possibility has significant implications for direct and indirect searches for dark matter.

5 pages, 3 figures

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Cited by in corpus (16)

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• PeV-Scale Dark Matter as a Thermal Relic of a Decoupled Sector
• Toward (Finally!) Ruling Out Z and Higgs Mediated Dark Matter Models
• Inflatable Dark Matter
• Galactic PeV neutrinos from dark matter annihilation
• Electroweak Dark Matter at Future Hadron Colliders
• 10 GeV neutralino dark matter and light stau in the MSSM
• WIMPs with GUTs: Dark Matter Coannihilation with a Lighter Species
• Status of low mass LSP in SUSY
• Novel Gamma-Ray Signatures of PeV-Scale Dark Matter
• Faint Dark Matter Annihilation Signals and the Milky Way's Supermassive Black Hole
• Daughters mimic sterile neutrinos (almost!) perfectly
• Everything You Always Wanted to Know About Dark Matter Elastic Scattering Through Higgs Loops But Were Afraid to Ask
• Dark Gamma Ray Bursts