Refined bounds on MeV-scale thermal dark sectors from BBN and the CMB
By N. Sabti, J.B.G. Alvey, Miguel Escudero, M. Fairbairn, D. Blas. Journal of Cosmology and Astroparticle Physics, 2019
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New light states thermally coupled to the Standard Model plasma alter the expansion history of the Universe and impact the synthesis of the primordial light elements. In this work, we carry out an exhaustive and precise analysis of the implications of MeV-scale BSM particles in Big Bang Nucleosynthesis (BBN) and for Cosmic Microwave Background (CMB) observations. We find that BBN observations set a lower bound on the thermal dark matter mass of mχ > 0.4 MeV at 2σ. This bound is independent of the spin and number of internal degrees of freedom of the particle, of the annihilation being s-wave or p-wave, and of the annihilation final state. Furthermore, we show that current BBN plus CMB observations constrain purely electrophilic and neutrinophilic BSM species to have a mass, mχ > 3.7 MeV at 2σ. We explore the reach of future BBN measurements and show that upcoming CMB missions should improve the bounds on light BSM thermal states to mχ > (10−15) MeV. Finally, we demonstrate that very light BSM species thermally coupled to the SM plasma are highly disfavoured by current cosmological observations.
Subfields: Artificial Intelligence, Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/9ba936ef4e504db5a5891a5061f21ac70f5ef68e
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Citations in the corpus
- Precision early universe thermodynamics made simple: Neff and neutrino decoupling in the Standard Model and beyond (2020, methodology): “We note that the method has already been applied to study: i) the BBN effect of MeV-scale thermal dark sectors [1, 72], ii) the impact on BBN of invisible neutrino decays [71], iii) the cosmological consequences of light and weakly coupled flavorful gauge bosons [73], iv) Neff constraints on dark ph”