The Proton That Stayed Small
Source and redistribution notice, checked 2026-09-22

1. Maisenbacher, Lothar; Wirthl, Vitaly; Matveev, Arthur; Grinin, Alexey;
Pohl, Randolf; Hänsch, Theodor W.; Udem, Thomas.
Sub-part-per-trillion test of the Standard Model with atomic hydrogen.
Nature 650, 845-851 (2026). DOI 10.1038/s41586-026-10124-3.
https://www.nature.com/articles/s41586-026-10124-3
The article's Rights and permissions section states CC BY 4.0.
https://creativecommons.org/licenses/by/4.0/

Included under that licence with attribution:
data/comparison.csv: unchanged Figure 1 source CSV (including its source-year
and blank-DOI metadata). No third-party exception was found for this numerical table.
data/control-2026.json: factual transcription of equations (4)-(10), Table 1
and Methods equations (16)-(18), reorganised into named JSON fields.
data/rydberg.json (Garching entry): the Rydberg constant printed in the
section on R-infinity and rp from atomic hydrogen, with the paired radius.
data/single-scan.json: selected worksheet values from Figure 2 source XLSX,
sheet 'd, from fit to exp.'. The expected extrapolation is a separate check
target from 'd, extrapolation'; it is never a fit input.
Source file URLs and byte hashes are in record.json and the research README.
The research data directory also retains the unchanged CC BY Figure 2 workbook.
All plots and synthetic edits are newly computed here; they are not paper figures.
Three short sentences of the article are quoted on the page with attribution, one of
them from the abstract with its reference numerals omitted.

2. Randolf Pohl and 31 coauthors, The size of the proton.
Nature 466, 213-216 (2010). DOI 10.1038/nature09250.
https://www.nature.com/articles/nature09250
Checking copy: https://web.mit.edu/OLYMPUS/DOCUMENTS/nature09250.pdf
The paper prints copyright 2010 Macmillan Publishers Limited, all rights reserved.
data/claim-2010.json is our small, attributed transcription of factual
measurements and coefficients, and of the Rydberg constant the paper prints on
p. 216. The short quotations are credited on the page.
This notice does not grant an open licence to the publisher's article.
No paper, supplement or publisher figure is redistributed.

3. Peter J. Mohr, David B. Newell, Barry N. Taylor and Eite Tiesinga.
CODATA recommended values of the fundamental physical constants: 2022.
Journal of Physical and Chemical Reference Data 54, 033105 (2025).
DOI 10.1063/5.0279860.
https://physics.nist.gov/cuu/pdf/JPCRD2022CODATA.pdf
The PDF prints copyright 2025 by the U.S. Secretary of Commerce on behalf of
the United States, all rights reserved. data/constants-2022.json contains
attributed numerical constants; data/context.json contains the recommended
radius and bibliographic facts; data/rydberg.json contains the recommended
Rydberg constant and the paired radius from Table XVI. None of these files
relicenses the publication. One sentence of its overview (section I.B) is quoted
on the page with attribution.
The PDF is not redistributed.

3a. Peter J. Mohr, Barry N. Taylor and David B. Newell.
CODATA recommended values of the fundamental physical constants: 2006.
Reviews of Modern Physics 80, 633-730 (2008). DOI 10.1103/RevModPhys.80.633.
Values read in the author version, arXiv:0801.0028v1:
https://arxiv.org/abs/0801.0028
Only the Rydberg constant 10 973 731.568 527(73) per metre and its paired
proton radius 0.8768(69) fm are transcribed, in data/rydberg.json, with
attribution. Neither the article nor the arXiv copy is redistributed.

4. R. G. Bullis, W. L. Tavis, M. R. Weiss, J. Orellana Cisneros,
A. J. Cheeseman, U. D. Jentschura and D. C. Yost.
Precision Spectroscopy of 2S-nS Transitions in Atomic Hydrogen:
A Determination of the Proton Charge Radius.
Physical Review Letters 136, 123001 (23 March 2026). DOI 10.1103/lgl2-6cb8.
https://journals.aps.org/prl/abstract/10.1103/lgl2-6cb8
Publisher: copyright 2026 American Physical Society.
Only a factual radius estimate, its Rydberg frequency and bibliographic facts
are transcribed, in data/context.json and data/rydberg.json. No article or
dataset is redistributed.
Public author record: https://arxiv.org/abs/2604.26401v1

5. Gerald A. Miller, The Proton Radius Puzzle, arXiv:2604.15546v2,
revised 25 April 2026, prepared for Encyclopedia of Nuclear Physics.
https://arxiv.org/abs/2604.15546v2
Used as a linked specialist review and for bibliographic facts only.
No preprint text or figures are redistributed.

6. Lothar Maisenbacher, Dataset for the hydrogen 2S-6P transition measurement
at MPQ, version 1, 11 February 2026. DOI 10.5281/zenodo.15874385.
https://zenodo.org/records/15874385
The record states CC BY 4.0. Linked for the scope of the available data;
the archive and its analysis are not republished or claimed as reproduced here.

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