The proposed measurement is a dedicated study of the exclusive electroproduction process, 1 H(e, e ′ p)π 0 , in the backward-angle regime (u-channel process) above the resonance region. Here, the produced π 0 is emitted 180 degrees opposite to the virtual-photon momentum (at large momentum transfer). This study also aims to apply the well-known Rosenbluth separation technique that provides the model-independent (L/T) differential cross-section at the never explored u-channel kinematics region (−t = −t max , −u = −u min ).Currently, the "soft-hard transition" in u-channel meson production remains an interesting and unexplored subject. The available theoretical frameworks offer competing interpretations for the observed backward-angle cross section peaks. In a "soft" hadronic Regge exchange description, the backward meson production comes from the interference between nucleon exchange and the meson produced via re-scattering within the nucleon. Whereas in the "hard" GPD-like backward collinear factorization regime, the scattering amplitude factorizes into a hard subprocess amplitude and baryon to meson transition distribution amplitudes (TDAs), otherwise known as super skewed parton distributions (SuperSPDs). Both TDAs and SPDs are universal non-perturbative objects of nucleon structure accessible only through backward-angle kinematics.The separated cross sections: σ T , σ L and (σ T /σ L ) ratio at Q 2 =2-6 GeV 2 , provide a direct test of two predictions from the TDA model: σ T ∝ 1/Q 8 and the σ T ≫ σ L in u-channel kinematics. The magnitude and u-dependence of the separated cross sections also provide a direct connection to the re-scattering Regge picture. The extracted interaction radius (from u-dependence) at different Q 2 can be used to study the soft-hard transition in the u-channel kinematics. The acquisition of these data will be an important step forward in validating the existence of a backward factorization scheme (TDA and SuperSPD) of the nucleon structure function and establishing its applicable kinematic range.

Backward-angle meson electroproduction above the resonance region, which was previously ignored, is anticipated to offer unique access to the three quark plus sea component of the nucleon wave function. In this letter, we present the first complete separation of the four electromagnetic structure functions above the resonance region in exclusive ω electroproduction off the proton, ep → e ′ pω, at central Q 2 values of 1.60, 2.45 GeV 2 , at W = 2.21 GeV. The results of our pioneering −u ≈ −umin study demonstrate the existence of a unanticipated backward-angle cross section peak and the feasibility of full L/T/LT/TT separations in this never explored kinematic territory. At Q 2 =2.45 GeV 2 , the observed dominance of σT over σL, is qualitatively consistent with the collinear QCD description in the near-backward regime, in which the scattering amplitude factorizes into a hard subprocess amplitude and baryon to meson transition distribution amplitudes (TDAs): universal non-perturbative objects only accessible through backward angle kinematics.Deep exclusive reactions have recently gained much attention, as they provide direct access to the internal