A multidimensional study of the structure function ratio σLT0 from hard exclusive π+ electro-production off protons in the GPD regime

CLAS Collaboration

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A multidimensional extraction of the structure function ratio σLT0 from the hard exclusive e→p→e+ reaction above the resonance region has been performed. The study was done based on beam-spin 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/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 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 Q2, while the GPD model is more appropriate at high Q2.

Original languageEnglish
Article number137761
Number of pages7
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Early online date13 Feb 2023
Publication statusPublished - 10 Apr 2023

Bibliographical note

Funding Information:
We acknowledge the outstanding efforts of the staff of the Accelerator and the Physics Divisions at Jefferson Lab in making this experiment possible. We owe much gratitude to P. Kroll for many fruitful discussions concerning the interpretation of our results. This work was supported in part by the U.S. Department of Energy , the National Science Foundation (NSF), the Italian Istituto Nazionale di Fisica Nucleare ( INFN ), the French Centre National de la Recherche Scientifique (CNRS), the French Commissariat pour l′Energie Atomique , the UK Science and Technology Facilities Council , the National Research Foundation ( NRF ) of Korea, the Helmholtz-Forschungsakademie Hessen für FAIR (HFHF), the Ministry of Science and Higher Education of the Russian Federation and the National Natural Science Foundation of China . The Southeastern Universities Research Association (SURA) operates the Thomas Jefferson National Accelerator Facility for the U.S. Department of Energy under Contract No. DE-AC05-06OR23177.

Publisher Copyright:
© 2023 The Author(s)


  • CLAS12
  • Eletroproduction
  • Exclusive single pion
  • GPD

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