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arXiv · 1011.3519

Proton size anomaly

Vernon Barger·Cheng-Wei Chiang·Wai-Yee Keung·Danny Marfatia
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Abstract

A measurement of the Lamb shift in muonic hydrogen yields a charge radius of the proton that is smaller than the CODATA value by about 5 standard deviations. We explore the possibility that new scalar, pseudoscalar, vector, and tensor flavor-conserving nonuniversal interactions may be responsible for the discrepancy. We consider exotic particles that among leptons, couple preferentially to muons, and mediate an attractive nucleon-muon interaction. We find that the many constraints from low energy data disfavor new spin-0, spin-1 and spin-2 particles as an explanation.

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Vernon Barger, Cheng-Wei Chiang, Wai-Yee Keung, Danny Marfatia. 2011-03-18. Proton size anomaly. https://doi.org/10.1103/physrevlett.106.153001

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