Experiments towards resolving the proton charge radius puzzle
نویسندگان
چکیده
We review the status of the proton charge radius puzzle. Emphasis is given to the various experiments initiated to resolve the conflict between the muonic hydrogen results and the results from scattering and regular hydrogen spectroscopy. 1 The proton charge radius puzzle The historical route to the proton charge radius (rp) is from elastic electron-proton scattering. In a completely complementary fashion, it has been obtained also from “high-precision” laser spectroscopy of hydrogen (H). Since a few years, “high-sensitivity” laser spectroscopy of muonic hydrogen (μp) offers a third way. The value extracted from μp with a relative accuracy of 5×10−4 is an order of magnitude more accurate than obtained from the other methods. Yet the value is 4% smaller than derived from electron-proton scattering and H spectroscopy with a disagreement at the 7σ level [1–5]. In the last five years as summarized in [6, 7] various cross checks and refinements of boundstate QED calculations needed for the extraction of rp from μp have been performed, together with investigations of the proton structure. Several suggestions in the field of “beyond standard model” BSM physics have been articulated, re-analysis of scattering data have been carried out and new experiments have been initiated. Despite this, presently the discrepancy still persists and the resolution ae-mail: [email protected] bAlso at: Ludwig-Maximilians-Universität, 80539 Munich, Germany. DOI: 10.1051/ C © Owned by the authors, published by EDP Sciences, 201 / 0 0 (201 ) 201 epjconf EPJ Web of Conferences , 1 0
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تاریخ انتشار 2016