CMB bounds on dark matter annihilation : Nucleon energy losses after recombination

• We consider the propagation and energy losses of protons and antiprotons produced by dark matter annihilation at redshifts 100 < z less than or similar to 2000. In the case of dark matter annihilations into quarks, gluons and weak gauge bosons, protons and antiprotons carry about 20% of the energy injected into e(+/-) and gamma's, but their interactions are normally neglected when deriving cosmic microwave background bounds from altered recombination histories. Here, we follow numerically the energy-loss history of typical protons/antiprotons in the cosmological medium. We show that about half of their energy is channeled into photons and e(+/-), and we present a simple prescription to estimate the corresponding strengthening of the cosmic microwave background bounds on the dark matter annihilation cross section.

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NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

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