2003/09/11 by Gary Steigman, Steigman, Gary
Physics and Astronomy · #Astrophysics (astro-ph) #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle physics theoretical and experimental studies #astro-ph #hep-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0309338
To appear in the proceedings of the XVth Rencontres de Blois, Physical Cosmology: New Results in Cosmology and the Coherence of the Standard Model; 10 pages, 6 figures
arxiv created 2003/09/11 · openalex publication_date 2003/09/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A key pillar of modern cosmology, Big Bang Nucleosynthesis (BBN) offers a probe of the particle content and expansion rate of the Universe a mere few minutes after the beginning. When compared with the BBN predictions, the observationally inferred primordial abundances of deuterium and helium-4 provide an excellent baryometer and chronometer respectively. Several hundred thousand years later, when the Cosmic Background Radiation (CBR) photons began progagating freely, the spectrum of temperature fluctuations imprinted on them also encoded information about the baryon density and the expansion rate. Comparing the constraints imposed by BBN with those from the CBR reveals a consistent picture of the Universe at these two very widely separated epochs. Combining these probes leads to new, tighter constraints on the baryon density at present and on possible new physics beyond the standard model of particle physics.