File:Universe-09-00183.pdf
From Wikimedia Commons, the free media repository
Jump to navigation
Jump to search
Size of this JPG preview of this PDF file: 424 × 600 pixels. Other resolutions: 170 × 240 pixels | 339 × 480 pixels | 543 × 768 pixels | 1,239 × 1,752 pixels.
Original file (1,239 × 1,752 pixels, file size: 1.38 MB, MIME type: application/pdf, 18 pages)
File information
Structured data
Captions
Summary[edit]
DescriptionUniverse-09-00183.pdf |
English: We explore the effect of neutron lifetime and its uncertainty on standard big bang nucleosynthesis (BBN). BBN describes the cosmic production of the light nuclides, 1H, D, 3H+3He, 4He, and 7Li+7Be, in the first minutes of cosmic time. The neutron mean life τn has two roles in modern BBN calculations: (1) it normalizes the matrix element for weak n↔p interconversions, and (2) it sets the rate of free neutron decay after the weak interactions freeze-out. We review the history of the interplay between τn measurements and BBN, and present a study of the sensitivity of the light element abundances to the modern neutron lifetime measurements. We find that τn uncertainties dominate the predicted 4He error budget, but these theory errors remain smaller than the uncertainties in 4He observations, even with the dispersion in recent neutron lifetime measurements. For the other light element predictions, τn contributes negligibly to their error budget. Turning the problem around, we combine present BBN and cosmic microwave background (CMB) determinations of the cosmic baryon density to predict a “cosmologically preferred” mean life of τn(BBN+CMB)=870±16s, which is consistent with experimental mean life determinations. We show that if future astronomical and cosmological helium observations can reach an uncertainty of σobs(Yp)=0.001 in the 4He mass fraction Yp, this could begin to discriminate between the mean life determinations. |
Date | |
Source |
https://www.mdpi.com/2218-1997/9/4/183 https://doi.org/10.3390/universe9040183 |
Author | Tsung-Han Yeh, Keith A. Olive and Brian D. Fields |
Licensing[edit]
This file is licensed under the Creative Commons Attribution 4.0 International license.
- You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
- Under the following conditions:
- attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
File history
Click on a date/time to view the file as it appeared at that time.
Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 10:23, 14 April 2023 | 1,239 × 1,752, 18 pages (1.38 MB) | Pamputt (talk | contribs) | Uploaded a work by Tsung-Han Yeh, Keith A. Olive and Brian D. Fields from https://www.mdpi.com/2218-1997/9/4/183 https://doi.org/10.3390/universe9040183 with UploadWizard |
You cannot overwrite this file.
File usage on Commons
There are no pages that use this file.
Metadata
This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.
Short title | The Neutron Mean Life and Big Bang Nucleosynthesis |
---|---|
Image title | We explore the effect of neutron lifetime and its uncertainty on standard big bang nucleosynthesis (BBN). BBN describes the cosmic production of the light nuclides, 1H, D, 3H+3He, 4He, and 7Li+7Be, in the first minutes of cosmic time. The neutron mean life n has two roles in modern BBN calculations: (1) it normalizes the matrix element for weak n p interconversions, and (2) it sets the rate of free neutron decay after the weak interactions freeze-out. We review the history of the interplay between n measurements and BBN, and present a study of the sensitivity of the light element abundances to the modern neutron lifetime measurements. We find that n uncertainties dominate the predicted 4He error budget, but these theory errors remain smaller than the uncertainties in 4He observations, even with the dispersion in recent neutron lifetime measurements. For the other light element predictions, n contributes negligibly to their error budget. Turning the problem around, we combine present BBN and cosmic microwave background (CMB) determinations of the cosmic baryon density to predict a ``cosmologically preferred mean life of n(BBN+CMB) = 870 16 s, which is consistent with experimental mean life determinations. We show that if future astronomical and cosmological helium observations can reach an uncertainty of obs(Yp) = 0.001 in the 4He mass fraction Yp, this could begin to discriminate between the mean life determinations. |
Author | |
Keywords |
|
Software used | LaTeX with hyperref |
Conversion program | pdfTeX-1.40.21 |
Encrypted | no |
Page size | 595.276 x 841.89 pts (A4) |
Version of PDF format | 1.7 |