A robust upper limit on Neff from BBN, circa 2011

By G. Mangano, P. Serpico. 2011

159 citations recorded by the source corpus.

Abstract We derive here a robust bound on the effective number of neutrinos from constraints on primordial nucleosynthesis yields of deuterium and helium. In particular, our results are based on very weak assumptions on the astrophysical determination of the helium abundance, namely that the minimum effect of stellar processing is to keep constant (rather than increase, as expected) the helium content of a low-metallicity gas. Using the results of a recent analysis of extragalactic HII regions as upper limit, we find that Δ N eff ⩽ 1 at 95% C.L., quite independently of measurements on the baryon density from cosmic microwave background anisotropy data and of the neutron lifetime input. In our approach, we also find that primordial nucleosynthesis alone has no significant preference for an effective number of neutrinos larger than the standard value. The ∼ 2 σ hint sometimes reported in the literature is thus driven by CMB data alone and/or is the result of a questionable regression protocol to infer a measurement of primordial helium abundance.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/0a0c16524924f40bb714277ec6daaef6fdcd5c9c

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In Astronomy and Astrophysics

1. J. Carlstrom
2. M. Joy
3. Joseph J. Mohr
4. Joachim Kopp
5. L. Shaw
6. Oliver Zahn
7. K. Story
8. W. Holzapfel

In Nuclear and High Energy Physics

1. T. Schwetz
2. M. Maltoni
3. Joachim Kopp
4. P. Machado
5. M. Shaevitz
6. G. Karagiorgi
7. J. Spitz
8. J. Conrad

Citations in the corpus

• Sterile neutrino oscillations: the global picture (2013, methodology): “Constraints from Big Bang Nucleosynthesis on Neff have been considered recently in [57].”
• Sterile Neutrino Fits to Short-Baseline Neutrino Oscillation Measurements (2012, background): “However, the need for additional information from both appearance and disappearance experiments provides strong motivation for pursuing the future experiments discussed in this paper.”
• A MEASUREMENT OF THE DAMPING TAIL OF THE COSMIC MICROWAVE BACKGROUND POWER SPECTRUM WITH THE SOUTH POLE TELESCOPE (2011, methodology): “Mangano & Serpico (2011) use 4He and deuterium abundances to provide a conservative upper limit of Neff 4.2 (95% CL).”