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Title: Review of two-photon exchange in electron scattering

Journal Article · · Progress in Particle and Nuclear Physics

We review the role of two-photon exchange (TPE) in electron-hadron scattering, focusing in particular on hadronic frameworks suitable for describing the low and moderate Q^2 region relevant to most experimental studies. We discuss the effects of TPE on the extraction of nucleon form factors and their role in the resolution of the proton electric to magnetic form factor ratio puzzle. The implications of TPE on various other observables, including neutron form factors, electroproduction of resonances and pions, and nuclear form factors, are summarized. Measurements seeking to directly identify TPE effects, such as through the angular dependence of polarization measurements, nonlinear epsilon contributions to the cross sections, and via e+p to e-p cross section ratios, are also outlined. In the weak sector, we describe the role of TPE and gamma-Z interference in parity-violating electron scattering, and assess their impact on the extraction of the strange form factors of the nucleon and the weak charge of the proton.

Research Organization:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
DOE Contract Number:
AC05-06OR23177
OSTI ID:
1024480
Report Number(s):
JLAB-THY-11-1365; DOE/OR/23177-1550; arXiv:1105.0951; PPNPDB; TRN: US1104751
Journal Information:
Progress in Particle and Nuclear Physics, Vol. 66, Issue 4; ISSN 0146-6410
Country of Publication:
United States
Language:
English