Two-Boson Exchange Physics: A Brief Review

Abstract

Current status of the two-boson exchange contributions to elastic electron-proton scattering, both for parity conserving and parity-violating, is briefly reviewed. How the discrepancy in the extraction of elastic nucleon form factors between unpolarized Rosenbluth and polarization transfer experiments can be understood, in large part, by the two-photon exchange corrections is discussed. We also illustrate how the measurement of the ratio between positron-proton and electron-proton scattering can be used to differentiate different models of two-photon exchange. For the parity-violating electron-proton scattering, the interest is on how the two-boson exchange (TBE), γZ-exchange in particular, could affect the extraction of the long-sought strangeness form factors. Various calculations all indicate that the magnitudes of effect of TBE on the extraction of strangeness form factors is small, though can be large percentage-wise in certain kinematics.

6 pages, 5 figures, prepared for Proceedings of the fifth Asia-Pacific Conference on Few-Body Problems in Physics (APFB2011), Seoul, Korea, August 22-26, 2011, to appear in Few-Body Systems, November 2011

References in corpus (7)

• Global analysis of proton elastic form factor data with two-photon exchange corrections
• Review of two-photon exchange in electron scattering
• Two-Photon Physics in Hadronic Processes
• Measurement of Strange Quark Contributions to the Vector Form Factors of the Proton at Q**2=0.22 (GeV/c)**2
• Model-dependence of the $\gamma Z$ dispersion correction to the parity-violating asymmetry in elastic $ep$ scattering
• Is there model-independent evidence of the two-photon-exchange effect in the electron-proton elastic scattering cross section?
• New formulation of gamma-Z box corrections to the weak charge of the proton

Cited by in corpus (1)

• Two-photon exchange corrections to ${\gamma }^{\ast }N\Delta$ form factors for $Q^2\le 4$ (Gev/$c$)${}^2$