Two-Photon Exchange: Future Experimental Prospects
Abstract The proton elastic form factor ratio is accessible in unpolarized Rosenbluth-type experiments as well as experiments which make use of polarization degrees of freedom. The extracted values show a distinct discrepancy, growing with $$Q^2$$ Q 2 . Three recent experiments tested the proposed e...
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| Format: | Article |
| Language: | English |
| Published: |
Springer Vienna,
2021-11-24T16:16:33Z.
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| Online Access: | Get fulltext |
| Summary: | Abstract The proton elastic form factor ratio is accessible in unpolarized Rosenbluth-type experiments as well as experiments which make use of polarization degrees of freedom. The extracted values show a distinct discrepancy, growing with $$Q^2$$ Q 2 . Three recent experiments tested the proposed explanation, two-photon exchange, by measuring the positron-proton to electron-proton cross section ratio. In the results, a hard two-photon exchange effect at the couple-of-percent level is visible, significantly different from theoretical calculation. Theory at larger momentum transfer remains untested. This paper discusses the possibilities for future measurements at larger momentum transfer. Office of Nuclear Physics of the U.S. Department of Energy (Grant DE-FG02-94ER40818) |
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