2019/10/31 by Nashwan Sabti, James Alvey, Miguel Escudero +2 · 2 citations
Computer Science · Physics and Astronomy · #Annihilation #Big Bang (financial markets) #Computational Physics and Python Applications #Cosmic background radiation #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark matter #Thermal #Universe #astro-ph.CO #hep-ph
paper · pdf · doi:10.1088/1475-7516/2020/01/004
28 pages, 10 figures, 7 tables. v2. References and minor clarifications added. Matches published version in JCAP
openalex created_date 2019/10/10 · arxiv created 2019/11/27 · openalex publication_date 2020/01/02 · arxiv updated 2020/01/15 · openalex updated_date 2026/08/06
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 m χ > 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, m χ > 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 m χ > (10−15) MeV. Finally, we demonstrate that very light BSM species thermally coupled to the SM plasma are highly disfavoured by current cosmological observations.