Publications
Publication Information
| Title | A small proton charge radius from an electron–proton scattering experiment | ||
| Authors | W. Xiong, Ashot Gasparian, H. Gao, D. Dutta, M. Khandaker, N. Liyanage, E. Pasyuk, C. Peng, X. Bai, L. Ye, K. Gnanvo, C. Gu, M. Levillain, X. Yan, D. Higinbotham, M. Meziane, Z. Ye, Krishna Adhikari, B. Aljawrneh, H. Bhatt, D. Bhetuwal, J. Brock, Volker Burkert, C. Carlin, A. Deur, D. Di, J. Dunne, P. Ekanayaka, L. El Fassi, B. Emmich, L. Gan, O. Glamazdin, M. Kabir, A. Karki, C. Keith, S. Kowalski, V. Lagerquist, I. Larin, T. Liu, A. Liyanage, J. Maxwell, D. Meekins, S. Nazeer, V. Nelyubin, H. Nguyen, P. Pedroni, C. Perdrisat, J. Pierce, V. Punjabi, M. Shabestari, A. Shahinyan, R. Silwal, S. Stepanyan, A. Subedi, V. Tarasov, N. Ton, Y.-W. Zhang, Z. Zhao | ||
| JLAB number | JLAB-PHY-19-3107 | ||
| LANL number | (None) | ||
| Other number | DOE/OR/23177-4853 | ||
| Document Type(s) | (Journal Article) | ||
| Associated with EIC: | No | ||
| Supported by Jefferson Lab LDRD Funding: | No | ||
| Funding Source: | Nuclear Physics (NP) | ||
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Journal Compiled for Nature Volume 575 Issue 7781 Page(s) 147-150 Refereed | |||
| Publication Abstract: | Elastic electronproton scattering (ep) and the spectroscopy of hydrogen atoms are the two methods traditionally used to determine the proton charge radius, rp. In 2010, a new method using muonic hydrogen atoms1 found a substantial discrepancy compared with previous results2, which became known as the proton radius puzzle. Despite experimental and theoretical efforts, the puzzle remains unresolved. In fact, there is a discrepancy between the two most recent spectroscopic measurements conducted on ordinary hydrogen3,4. Here we report on the proton charge radius experiment at Jefferson Laboratory (PRad), a high-precision ep experiment that was established after the discrepancy was identified. We used a magnetic-spectrometer-free method along with a windowless hydrogen gas target, which overcame several limitations of previous ep experiments and enabled measurements at very small forward-scattering angles. Our result, rp = 0.831 ± 0.007stat ± 0.012syst femtometres, is smaller than the most recent high-precision ep measurement5 and 2.7 standard deviations smaller than the average of all ep experimental results6. The smaller rp we have now measured supports the value found by two previous muonic hydrogen experiments1,7. In addition, our finding agrees with the revised value (announced in 2019) for the Rydberg constant8one of the most accurately evaluated fundamental constants in physics. | ||
| Experiment Numbers: | E12-11-106 | ||
| Group: | Hall B | ||
| Document: | |||
| DOI: | https://doi.org/10.1038/s41586-019-1721-2 | ||
| Accepted Manuscript: | |||
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