Jan 26 – 30, 2015
Bormio, Italy
Europe/Berlin timezone

Two-photon exchange corrections in elastic electron-proton scattering

Jan 26, 2015, 5:39 PM
Bormio, Italy

Bormio, Italy


Mr Oleksandar Tomalak


The measured value of the proton charge radius from the Lamb shift of energy levels in muonic hydrogen is in strong contradiction, by 7-8 standard deviations, with the value obtained with electronic hydrogen spectroscopy and the value extracted from the unpolarized electron-proton scattering data. The precise determination of the proton radius from scattering experiments requires the account of higher order corrections, among which two photon exchange (TPE) diagram gives the dominant contribution. The elastic contribution to TPE correction was studied with the fixed momentum transfer dispersion relations and compared to the hadronic model with off-shell photon-nucleon vertexes. The dispersion relations formalism with one subtraction was proposed. Theoretical predictions of TPE elastic contribution to the unpolarized elastic electron-proton scattering and polarization transfer observables in the low momentum transfer region were made. The TPE formalism was generalized to the case of massive leptons and the elastic contribution was evaluated in the hadronic model for the kinematics of upcoming muon-proton scattering experiment (MUSE). The recoil correction to the leading-Q2 term of TPE correction was found.

Primary author

Mr Oleksandr Tomalak (Johannes Gutenberg-Universität Mainz)

Presentation materials