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Phys. Rev. Lett. 94, 022001 (2005) [4 pages]

Constraints on Proton Structure from Precision Atomic-Physics Measurements

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Stanley J. Brodsky1,*, Carl E. Carlson2,†, John R. Hiller3,‡, and Dae Sung Hwang4,§
1Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309, USA
2Particle Theory Group, Physics Department, College of William and Mary, Williamsburg, Virginia 23187-8795, USA
3Department of Physics, University of Minnesota-Duluth, Duluth, Minnesota 55812, USA
4Department of Physics, Sejong University, Seoul 143-747, Korea

See Also: Erratum

Received 11 August 2004; published 19 January 2005

Ground-state hyperfine splittings in hydrogen and muonium are very well measured. Their difference, after correcting for magnetic moment and reduced mass effects, is due solely to proton structure—the large QED contributions for a pointlike nucleus essentially cancel. The rescaled hyperfine difference depends on the Zemach radius, a fundamental measure of the proton, computed as an integral over a product of electric and magnetic proton form factors. The determination of the Zemach radius, (1.019±0.016)   fm, from atomic physics tightly constrains fits to accelerator measurements of proton form factors. Conversely, we can use muonium data to extract an experimental value for QED corrections to hydrogenic hyperfine data. There is a significant discrepancy between measurement and theory, in the same direction as a corresponding discrepancy in positronium.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.94.022001
DOI:
10.1103/PhysRevLett.94.022001
PACS:
14.20.Dh, 13.40.Gp, 31.30.–i

*Electronic address: sjbth@slac.stanford.edu

†Electronic address: carlson@physics.wm.edu

‡Electronic address: jhiller@d.umn.edu

§Electronic address: dshwang@sejong.ac.kr

See Also

Erratum: Stanley J. Brodsky, Carl E. Carlson, John R. Hiller, and Dae Sung Hwang, Erratum: Constraints on Proton Structure from Precision Atomic-Physics Measurements [Phys. Rev. Lett. 94, 022001 (2005)], Phys. Rev. Lett. 94, 169902 (2005).

Reply: J. L. Friar and I. Sick, Comment on “Constraints on Proton Structure from Precision Atomic-Physics Measurements”, Phys. Rev. Lett. 95, 049101 (2005).

Reply: Stanley J. Brodsky, Carl E. Carlson, John R. Hiller, and Dae Sung Hwang, Brodsky et al. Reply:, Phys. Rev. Lett. 95, 049102 (2005).

 
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