A multidimensional study of the structure function ratio _LT''/₀ from hard exclusive electro-production off protons in the GPD regime

A multidimensional extraction of the structure function ratio sigma(LT')/sigma(0) from the hard exclusive (e) over right arrowp -> e'n pi(+) reaction above the resonance region has been performed. The study was done based on beamspin asymmetry measurements using a 10.6 GeV incident electron beam on a liquid-hydrogen target and the CLAS12 spectrometer at Jefferson Lab. The measurements focus on the very forward regime (t/Q(2) << 1) with a wide kinematic range of x(B) in the valence regime (0.17 < x(B) < 0.55), and virtualities Q(2) << ranging from 1.5 GeV2 up to 6 GeV2. The results and their comparison to theoretical models based on Generalized Parton Distributions demonstrate the sensitivity to chiral-odd GPDs and the directly related tensor charge of the nucleon. In addition, the data is compared to an extension of a Regge formalism at high photon virtualities. It was found that the Regge model provides a better description at low Q(2), while the GPD model is more appropriate at high Q(2). (c) 2023 The Author(s). Published by Elsevier B.V.