Hard exclusive $\pi^{+}n$ electro production beam spin asymmetries off the proton in the GPD and TDA regimes

Abstract

Hard exclusive \pi^{+}π+n electro-production can be used to gain access to the 3D nucleon structure. The QCD factorisation mechanism in the “nearly forward region” (t/Q^{2}t/Q2 small) allows a description by Generalized Parton Distributions (GPDs), while for the “nearly backward” kinematic region (u/Q^{2}u/Q2 small) a description based on nucleon to pion transitions (TDAs) is available. The paper presents a measurement of single beam spin asymmetries to extract the A^{\sin\phi}_{LU}ALUsinϕ moments and the related cross section ratio \sigma_{LT^\prime}/\sigma_{0}σLT′/σ0 from the hard exclusive \pi^{+}π+ channel off the unpolarized hydrogen target in a wide range of kinematics based on data taken with the CLAS spectrometer at Jefferson Lab. In addition, under forward angles a detailed multidimensional study will be presented based on CLAS12 data and compared to theoretical predictions.