High-precision measurement of the proton elastic form factor ratio μpGE/GM at low Q2

We report a new, high-precision measurement of the proton elastic form factor ratio μpGE/GM for the four-momentum transfer squared Q2=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...

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Bibliographic Details
Published in:Physics letters. B 2011-11, Vol.705 (1-2), p.59-64
Main 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., Zhang, Y.
Format: Article
Language:English
Subjects:
ACCURACY
CORRECTIONS
ELECTROMAGNETIC FORM FACTORS
ELECTRON PROBES
ELECTRON-PROTON INTERACTIONS
Exact sciences and technology
EXTRACTION
FORM FACTORS
FOUR MOMENTUM TRANSFER
HYDROGEN
LAMB SHIFT
Nuclear physics
Physics
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
POLARIMETRY
POLARIZATION
PROTONS
RANGE
RECOILS
The physics of elementary particles and fields
YIELDS
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Summary:We report a new, high-precision measurement of the proton elastic form factor ratio μpGE/GM for the four-momentum transfer squared Q2=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 Q2 continues down to the lowest Q2 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 Q2 range. We obtain new extractions of the proton electric and magnetic radii, which are 〈rE2〉1/2=0.875±0.010 fm and 〈rM2〉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.
ISSN:0370-2693
1873-2445
DOI:10.1016/j.physletb.2011.10.002