The surprising influence of late charged current weak interactions on Big Bang Nucleosynthesis

The weak interaction charged current processes (νe+n↔p+e−; ν¯e+p↔n+e+; n↔p+e−+ν¯e) interconvert neutrons and protons in the early universe and have significant influence on Big Bang Nucleosynthesis (BBN) light-element abundance yields, particularly that for 4He. We demonstrate that the influence of...

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Main Authors: E. Grohs, George M. Fuller
Format: Article
Language:English
Published: Elsevier 2016-10-01
Series:Nuclear Physics B
Online Access:http://www.sciencedirect.com/science/article/pii/S0550321316302644
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spelling doaj-af45d632a71449d2bc8a67b5a1656f722020-11-25T01:09:32ZengElsevierNuclear Physics B0550-32131873-15622016-10-01911C95597310.1016/j.nuclphysb.2016.08.034The surprising influence of late charged current weak interactions on Big Bang NucleosynthesisE. Grohs0George M. Fuller1Department of Physics, University of Michigan, Ann Arbor, MI 48109, USADepartment of Physics, University of California, San Diego, La Jolla, CA 92093, USAThe weak interaction charged current processes (νe+n↔p+e−; ν¯e+p↔n+e+; n↔p+e−+ν¯e) interconvert neutrons and protons in the early universe and have significant influence on Big Bang Nucleosynthesis (BBN) light-element abundance yields, particularly that for 4He. We demonstrate that the influence of these processes is still significant even when they operate well below temperatures T∼0.7 MeV usually invoked for “weak freeze-out,” and in fact down nearly into the alpha-particle formation epoch (T≈0.1 MeV). This physics is correctly captured in commonly used BBN codes, though this late-time, low-temperature persistent effect of the isospin-changing weak processes, and the sensitivity of the associated rates to lepton energy distribution functions and blocking factors are not widely appreciated. We quantify this late-time influence by analyzing weak interaction rate dependence on the neutron lifetime, lepton energy distribution functions, entropy, the proton–neutron mass difference, and Hubble expansion rate. The effects we point out here render BBN a keen probe of any beyond-standard-model physics that alters lepton number/energy distributions, even subtly, in epochs of the early universe all the way down to near T=100 keV.http://www.sciencedirect.com/science/article/pii/S0550321316302644
collection DOAJ
language English
format Article
sources DOAJ
author E. Grohs
George M. Fuller
spellingShingle E. Grohs
George M. Fuller
The surprising influence of late charged current weak interactions on Big Bang Nucleosynthesis
Nuclear Physics B
author_facet E. Grohs
George M. Fuller
author_sort E. Grohs
title The surprising influence of late charged current weak interactions on Big Bang Nucleosynthesis
title_short The surprising influence of late charged current weak interactions on Big Bang Nucleosynthesis
title_full The surprising influence of late charged current weak interactions on Big Bang Nucleosynthesis
title_fullStr The surprising influence of late charged current weak interactions on Big Bang Nucleosynthesis
title_full_unstemmed The surprising influence of late charged current weak interactions on Big Bang Nucleosynthesis
title_sort surprising influence of late charged current weak interactions on big bang nucleosynthesis
publisher Elsevier
series Nuclear Physics B
issn 0550-3213
1873-1562
publishDate 2016-10-01
description The weak interaction charged current processes (νe+n↔p+e−; ν¯e+p↔n+e+; n↔p+e−+ν¯e) interconvert neutrons and protons in the early universe and have significant influence on Big Bang Nucleosynthesis (BBN) light-element abundance yields, particularly that for 4He. We demonstrate that the influence of these processes is still significant even when they operate well below temperatures T∼0.7 MeV usually invoked for “weak freeze-out,” and in fact down nearly into the alpha-particle formation epoch (T≈0.1 MeV). This physics is correctly captured in commonly used BBN codes, though this late-time, low-temperature persistent effect of the isospin-changing weak processes, and the sensitivity of the associated rates to lepton energy distribution functions and blocking factors are not widely appreciated. We quantify this late-time influence by analyzing weak interaction rate dependence on the neutron lifetime, lepton energy distribution functions, entropy, the proton–neutron mass difference, and Hubble expansion rate. The effects we point out here render BBN a keen probe of any beyond-standard-model physics that alters lepton number/energy distributions, even subtly, in epochs of the early universe all the way down to near T=100 keV.
url http://www.sciencedirect.com/science/article/pii/S0550321316302644
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