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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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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