High-precision measurement of the proton elastic form factor ratio μpGE/G M at low Q 2

Zhan, X. et al. (2011) High-precision measurement of the proton elastic form factor ratio μpGE/G M at low Q 2. Physics Letters B, 705(1-2), pp. 59-64. (doi: 10.1016/j.physletb.2011.10.002)

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Abstract

We report a new, high-precision measurement of the proton elastic form factor ratio μpGE /GM for the four-momentum transfer squared Q 2 = 0.3–0.7 (GeV/c)2. The measurement was performed at Jefferson Lab (JLab) in Hall A using recoil polarimetry. With a total uncertainty of approximately 1%, the new data clearly show that the deviation of the ratio μpGE /GM from unity observed in previous polarization measurements at high Q 2 continues down to the lowest Q 2 value of this measurement. The updated global fit that includes the new results yields an electric (magnetic) form factor roughly 2% smaller (1% larger) than the previous global fit in this Q 2 range. We obtain new extractions of the proton electric and magnetic radii, which are r2 E 1/2 = 0.875 ± 0.010 fm and r2 M 1/2 = 0.867 ± 0.020 fm. The charge radius is consistent with other recent extractions based on the electron–proton interaction, including the atomic hydrogen Lamb shift measurements, which suggests a missing correction in the comparison of measurements of the proton charge radius using electron probes and the recent extraction from the muonic hydrogen Lamb shift.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Protopopescu, Dr Dan
Authors: Zhan, X., Allada, K., Armstrong, D.S., Arrington, J., Bertozzi, W., Boeglin, W., Chen, J.-P., Chirapatpimol, K., Choi, S., Chudakov, E., Cisbani, E., Decowski, P., Dutta, C., Frullani, S., Fuchey, E., Garibaldi, F., Gilad, S., Gilman, R., Glister, J., Hafidi, K., Hahn, B., Hansen, J.-O., Higinbotham, D.W., Holmstrom, T., Holt, R.J., Huang, J., Huber, G.M., Itard, F., de Jager, C.W., Jiang, X., Johnson, M., Katich, J., de Leo, R., LeRose, J.J., Lindgren, R., Long, E., Margaziotis, D.J., May-Tal Beck, S., Meekins, D., Michaels, R., Moffit, B., Norum, B.E., Olson, M., Piasetzky, E., Pomerantz, I., Protopopescu, D., Qian, X., Qiang, Y., Rakhman, A., Ransome, R.D., Reimer, P.E., Reinhold, J., Riordan, S., Ron, G., Saha, A., Sarty, A.J., Sawatzky, B., Schulte, E.C., Shabestari, M., Shahinyan, A., Shneor, R., Širca, S., Solvignon, P., Sparveris, N.F., Strauch, S., Subedi, R., Sulkosky, V., Vilardi, I., Wang, Y., Wojtsekhowski, B., Ye, Z., and Zhang, Y.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physics Letters B
Publisher:Elsevier BV
ISSN:0370-2693
ISSN (Online):1873-2445

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