Speaker
Description
The MUSE experiment at the Paul Scherrer Institute will measure low-energy muon-proton elastic scattering (muon momenta: 115--210 MeV) to determine the proton charge radius. This talk discusses the prospects for extracting the radius using dispersively improved chiral effective field theory (DI$\chi$EFT), which connects the proton's charge distribution to the form factor behavior while allowing data up to $Q^2 \sim 0.1$ GeV$^2$ to be used. We examine the sensitivity of the $\mu p$ cross section to the proton radius, theoretical uncertainties in the predictions, and the two-photon exchange correction. The optimal kinematics for radius extraction at MUSE are found at 210 MeV and $Q^2 \sim 0.05$-0.08 GeV$^2$. We compare muon and electron scattering in the same kinematics and provide predictions for both $\mu p$ and $ep$ cross sections as functions of the proton radius.
