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QED confronts the radius of the proton
Recent results on muonic hydrogen [1] and the ones compiled by CODATA on ordinary hydrogen and $ep$-scattering [2] are $5\sigma$ away from each other. Two reasons justify a further look at this subject: 1) One of the approximations used in [1] is not valid for muonic hydrogen. This amounts to a shif...
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Lenguaje: | eng |
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2010
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Acceso en línea: | https://dx.doi.org/10.1016/j.physletb.2011.01.025 http://cds.cern.ch/record/1300932 |
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author | De Rujula, A. |
author_facet | De Rujula, A. |
author_sort | De Rujula, A. |
collection | CERN |
description | Recent results on muonic hydrogen [1] and the ones compiled by CODATA on ordinary hydrogen and $ep$-scattering [2] are $5\sigma$ away from each other. Two reasons justify a further look at this subject: 1) One of the approximations used in [1] is not valid for muonic hydrogen. This amounts to a shift of the proton's radius by $\sim 3$ of the standard deviations of [1], in the "right" direction of data-reconciliation. In field-theory terms, the error is a mismatch of renormalization scales. Once corrected, the proton radius "runs", much as the QCD coupling "constant" does. 2) The result of [1] requires a choice of the "third Zemach moment". Its published independent determination is based on an analysis with a $p$-value --the probability of obtaining data with equal or lesser agreement with the adopted (fit form-factor) hypothesis-- of $3.92\times 10^{-12}$. In this sense, this quantity is not empirically known. Its value would regulate the level of "tension" between muonic- and ordinary-hydrogen results, currently {\it at most} $\sim 4\sigma$. There is no tension between the results of [1] and the proton radius determined with help of the analyticity of its form factors. |
id | cern-1300932 |
institution | Organización Europea para la Investigación Nuclear |
language | eng |
publishDate | 2010 |
record_format | invenio |
spelling | cern-13009322023-03-14T19:46:02Zdoi:10.1016/j.physletb.2011.01.025http://cds.cern.ch/record/1300932engDe Rujula, A.QED confronts the radius of the protonParticle Physics - PhenomenologyRecent results on muonic hydrogen [1] and the ones compiled by CODATA on ordinary hydrogen and $ep$-scattering [2] are $5\sigma$ away from each other. Two reasons justify a further look at this subject: 1) One of the approximations used in [1] is not valid for muonic hydrogen. This amounts to a shift of the proton's radius by $\sim 3$ of the standard deviations of [1], in the "right" direction of data-reconciliation. In field-theory terms, the error is a mismatch of renormalization scales. Once corrected, the proton radius "runs", much as the QCD coupling "constant" does. 2) The result of [1] requires a choice of the "third Zemach moment". Its published independent determination is based on an analysis with a $p$-value --the probability of obtaining data with equal or lesser agreement with the adopted (fit form-factor) hypothesis-- of $3.92\times 10^{-12}$. In this sense, this quantity is not empirically known. Its value would regulate the level of "tension" between muonic- and ordinary-hydrogen results, currently {\it at most} $\sim 4\sigma$. There is no tension between the results of [1] and the proton radius determined with help of the analyticity of its form factors.Recent results on muonic hydrogen (Pohl et al., 2010) [1] and the ones compiled by CODATA on ordinary hydrogen and ep -scattering (Mohr et al., 2008) [2] are 5 σ away from each other. Two reasons justify a further look at this subject: (1) One of the approximations used in Pohl et al. (2010) [1] is not valid for muonic hydrogen. This amounts to a shift of the proton's radius by ∼3 of the standard deviations of Pohl et al. (2010) [1] , in the “right” direction of data-reconciliation. In field-theory terms, the error is a mismatch of renormalization scales. Once corrected, the proton radius “runs”, much as the QCD coupling “constant” does. (2) The result of Pohl et al. (2010) [1] requires a choice of the “third Zemach moment”. Its published independent determination is based on an analysis with a p -value – the probability of obtaining data with equal or lesser agreement with the adopted (fit form-factor) hypothesis – of 3.92×10−12 . In this sense, this quantity is not empirically known. Its value would regulate the level of “tension” between muonic- and ordinary-hydrogen results, currently at most ∼4σ . There is no tension between the results of Pohl et al. (2010) [1] and the proton radius determined with help of the analyticity of its form-factors.Recent results on muonic hydrogen [1] and the ones compiled by CODATA on ordinary hydrogen and $ep$-scattering [2] are $5\sigma$ away from each other. Two reasons justify a further look at this subject: 1) One of the approximations used in [1] is not valid for muonic hydrogen. This amounts to a shift of the proton's radius by $\sim 3$ of the standard deviations of [1], in the "right" direction of data-reconciliation. In field-theory terms, the error is a mismatch of renormalization scales. Once corrected, the proton radius "runs", much as the QCD coupling "constant" does. 2) The result of [1] requires a choice of the "third Zemach moment". Its published independent determination is based on an analysis with a $p$-value --the probability of obtaining data with equal or lesser agreement with the adopted (fit form-factor) hypothesis-- of $3.92\times 10^{-12}$. In this sense, this quantity is not empirically known. Its value would regulate the level of "tension" between muonic- and ordinary-hydrogen results, currently {\it at most} $\sim 4\sigma$. There is no tension between the results of [1] and the proton radius determined with help of the analyticity of its form factors.arXiv:1010.3421CERN-PH-TH-2010-241CERN-PH-TH-2010-241oai:cds.cern.ch:13009322010-10-19 |
spellingShingle | Particle Physics - Phenomenology De Rujula, A. QED confronts the radius of the proton |
title | QED confronts the radius of the proton |
title_full | QED confronts the radius of the proton |
title_fullStr | QED confronts the radius of the proton |
title_full_unstemmed | QED confronts the radius of the proton |
title_short | QED confronts the radius of the proton |
title_sort | qed confronts the radius of the proton |
topic | Particle Physics - Phenomenology |
url | https://dx.doi.org/10.1016/j.physletb.2011.01.025 http://cds.cern.ch/record/1300932 |
work_keys_str_mv | AT derujulaa qedconfrontstheradiusoftheproton |