A multidimensional study of the structure function ratio from hard exclusive π+ electro-production off protons in the GPD regime
DOI
10.1016/j.physletb.2023.137761
Abstract
A multidimensional extraction of the structure function ratio σLT′/σ0 from the hard exclusive ⃗ep → e′nπ+ reaction above the resonance region has been performed. The study was done based on beam-spin asymmetry measure- ments 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/Q2 ≪ 1) with a wide kinematic range of xB in the valence regime (0.17 < xB < 0.55), and virtualities Q2 ranging from 1.5 GeV2 up to 6 GeV2. The results and their comparison to theoretical mod- els 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 Q2, while the GPD model is more appropriate at high Q2. Keywords: Exclusive single pion, Eletroproduction, GPD, CLAS12 PACS: 13.60.Le, 14.20.Dh, 14.40.Be, 24.85.+p
to the three-dimensional structure of the nucleon by correlating information about the transverse position and the longitudinal momentum of the quarks and gluons within the nucleon. Besides deeply virtual Compton scattering (DVCS), also deeply virtual meson production (DVMP) can be used to ac- cess GPDs. The factorization of the DVMP process into a perturbatively calculable hard-scattering part and two soft hadronic matrix elements, pa- rameterized by GPDs and a meson distribution amplitude (DA) as shown in Fig. 1 has been proven for longitudinally polarized virtual photons at large photon virtuality Q2, large energy W and fixed Bjorken-x [4, 5]. The con- tribution of transversely polarized virtual photons for which factorisation is not explicitly proven, is typically treated as a higher twist-effect in current phenomenological models [6].
Document Type
Article
Publication Date
4-10-2023
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Recommended Citation
Diehl, S., others (2023). A multidimensional study of the structure function ratio σLT'/σ0 from hard exclusive π+ electro-production off protons in the GPD regime. Phys. Lett. B, 839.