https://doi.org/10.1140/epjc/s10052-016-3966-3
Regular Article - Theoretical Physics
Two-photon exchange correction to muon–proton elastic scattering at low momentum transfer
1
Institut für Kernphysik, Johannes Gutenberg Universität, Mainz, Germany
2
PRISMA Cluster of Excellence, Johannes Gutenberg-Universität, Mainz, Germany
3
Department of Physics, Taras Shevchenko National University of Kyiv, Kiev, Ukraine
* e-mail: tomalak@uni-mainz.de
Received:
6
January
2016
Accepted:
21
February
2016
Published online:
7
March
2016
We evaluate the two-photon exchange (TPE) correction to the muon–proton elastic scattering at small momentum transfer. Besides the elastic (nucleon) intermediate state contribution, which is calculated exactly, we account for the inelastic intermediate states by expressing the TPE process approximately through the forward doubly virtual Compton scattering. The input in our evaluation is given by the unpolarized proton structure functions and by one subtraction function. For the latter, we provide an explicit evaluation based on a Regge fit of high-energy proton structure function data. It is found that, for the kinematics of the forthcoming muon–proton elastic scattering data of the MUSE experiment, the elastic TPE contribution dominates, and the size of the inelastic TPE contributions is within the anticipated error of the forthcoming data.
© The Author(s), 2016
