Proton form factor ratio ${\mu }_p{G}_E^p/G_M^p$ from double spin asymmetry

Journal Article · 15 March 2020 · Physical Review C

DOI: https://doi.org/10.1103/PhysRevC.101.035206 · OSTI ID:1605544

Liyanage, A. ; Armstrong, W.; Kang, H.; Maxwell, J.; Mulholland, J.; Ndukum, L.; Ahmidouch, A.; Albayrak, I.; Asaturyan, A.; Ates, O.; Baghdasaryan, H.; Boeglin, W.; Bosted, P.; Brash, E.; Butuceanu, C.; Bychkov, M.; Carter, P.; Chen, C.; Chen, J. -P.; Choi, S. ; Christy, E.; Covrig, S.; Crabb, D.; Danagoulian, S.; Daniel, A.; Davidenko, A. M.; Davis, B.; Day, D.; Deconinck, W.; Deur, A.; Dunne, J.; Dutta, D.; Fassi, L. El; Elaasar, M.; Ellis, C.; Ent, R.; Flay, D.; Frlez, E.; Gaskell, D.; Geagla, O.; German, J.; Gilman, R.; Gogami, T.; Gomez, J.; Goncharenko, Y. M.; Hashimoto, O.; Higinbotham, D.; Horn, T.; Huber, G. M.; Jones, M.; Jones, M. K.; Kalantarians, N.; Kang, H. -K.; Kawama, D.; Keppel, C.; Khandaker, M.; Kim, Y.; King, P. M.; Kohl, M.; Kovacs, K.; Kubarovsky, V.; Li, Y.; Liyanage, N.; Mamyan, V.; Markowitz, P.; Maruta, T.; Melnik, Y. M.; Meziani, Z. -E.; Mkrtchyan, A.; Mkrtchyan, H.; Mochalov, V. V.; Monaghan, P.; Narayan, A.; Nakamura, S. N.; Nuruzzaman,; Pentchev, L.; Pocanic, D.; Posik, M.; Puckett, A.; Qiu, X.; Reinhold, J.; Riordan, S.; Roche, J.; Rondón, O. A.; Sawatzky, B.; Shabestari, M.; Slifer, K.; Smith, G.; Soloviev, L. F.; Solvignon, P.; Tadevosyan, V.; Tang, L.; Vasiliev, A. N.; Veilleux, M.; Walton, T.; Wesselmann, F.; Wood, S. A.; Yao, H.; Ye, Z.; Zhu, L.

We report the ratio of the electric and magnetic form factor of the proton, $$\mu_p G_E^p/G_M^p$$, has been measured for elastic electron-proton scattering with polarized beam and target up to four-momentum transfer squared, $Q^2=5.66$ (GeV/c)$^2$ using the double spin asymmetry for target spin orientation aligned nearly perpendicular to the beam momentum direction. This measurement of $$\mu_p G_E^p/G_M^p$$ agrees with the $Q^2$ dependence of previous recoil polarization data and reconfirms the discrepancy at high $Q^2$ between the Rosenbluth and the polarization-transfer method with a different measurement technique and systematic uncertainties uncorrelated to those of the recoil-polarization measurements. The form factor ratio at $Q^2$=2.06 (GeV/c)$^2$ has been measured as $$\mu_p G_E^p/G_M^p = 0.720 \pm 0.176_{stat} \pm 0.039_{sys}$$, which is in agreement with an earlier measurement with the polarized target technique at similar kinematics. The form factor ratio at $Q^2$=5.66 (GeV/c)$^2$ has been determined as $$\mu_p G_E^p/G_M^p=0.244\pm0.353_{stat}\pm0.013_{sys}$$, which represents the highest $Q^2$ reach with the double spin asymmetry with polarized target to date.

• Research Organization: Mississippi State Univ., Mississippi State, MS (United States); Mississippi State Univ., Starkville, MS (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: National Science Foundation (NSF); Natural Sciences and Engineering Research Council of Canada (NSERC); USDOE Office of Science (SC), Nuclear Physics (NP); USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
• Contributing Organization: SANE Collaboration
• Grant/Contract Number: AC05-06OR23177; FG02-07ER41528; FG02-96ER40950; SC0003884; SC0013941
• OSTI ID: 1605544
• Report Number(s): DOE/OR/23177--4944; JLAB-PHY--20-3164; arXiv:1806.11156
• Journal Information: Physical Review C, Journal Name: Physical Review C Journal Issue: 3 Vol. 101; ISSN 2469-9985; ISSN PRVCAN
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English