Polarization transfer in $$\varvec{e}^+p \rightarrow e^+ \varvec{p}$$ scattering using the Super BigBite Spectrometer

The effects of multi-photon-exchange and other higher-order QED corrections on elastic electron-proton scattering have been a subject high experimental theoretical interest since the polarization transfer measurements proton electromagnetic form factor ratio $$G_E^p/G_M^p$$ at large momentum $$Q^2$$ conclusively established strong decrease this with for $$Q^2 \gtrsim 1$$ $$\hbox {GeV}^2$$ . This result is incompatible previous extractions quantity from cross section using Rosenbluth Separation technique. Much attention has focused extracting two-photon exchange (TPE) effect through unpolarized $$e^+p/e^-p$$ ratio, but in polarized can also reveal evidence hard exchange. Furthermore, it different sensitivity to generalized TPE factors, meaning that provide new information cannot be gleaned alone. Both $$\epsilon $$ -dependence fixed , deviations between positron-proton are key signatures TPE. A positron beam Jefferson Lab would present unique opportunity make first measurement transfer, comparison electron-scattering data place valuable constraints Here, we propose program Hall combines Super BigBite Spectrometer measuring recoil polarization, non-magnetic calorimetric detector triggering elastically scattered positrons. Though reduced current will restrict kinematic reach, very small systematic uncertainties, making clean probe