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Theoretical study of deeply virtual Compton Scattering off $^4$He

by Sara Fucini, Sergio Scopetta, Michele Viviani

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Submission summary

Authors (as registered SciPost users): Sara Fucini
Submission information
Preprint Link: scipost_201910_00026v1  (pdf)
Date submitted: Oct. 15, 2019, 2 a.m.
Submitted by: Sara Fucini
Submitted to: SciPost Physics Proceedings
Proceedings issue: 24th European Few Body Conference (EFB2019)
Ontological classification
Academic field: Physics
Specialties:
  • High-Energy Physics - Phenomenology
  • Nuclear Physics - Theory
Approach: Theoretical

Abstract

An interesting breakthrough in understanding the elusory inner content of nuclear systems in terms of partonic degrees of freedom is represented by deeply virtual Compton scattering processes. In such a way, tomographic view of nuclei and bound nucleons in coordinate space could be achieved for the first time. Moreover, nowadays experimental results for such a process considering 4He targets recently released at Jefferson Lab are available. In this talk, the recent results of our rigorous Impulse Approximation for DVCS off 4He, in terms of state-of-the-art models of the nuclear spectral function and of the parton structure of the bound proton, able to explain present data, has been shown.

Current status:
Has been resubmitted

Reports on this Submission

Report #1 by Anonymous (Referee 1) on 2019-10-16 (Invited Report)

  • Cite as: Anonymous, Report on arXiv:scipost_201910_00026v1, delivered 2019-10-16, doi: 10.21468/SciPost.Report.1230

Strengths

  1. Reports on a study of DVCS, which is a hot topic on both theoretical and experimental fronts.
  2. Presents an approach which is feasible and workable, yet realistic and rigorous enough by virtue of properly evaluating nuclear physics effects involving appropriate nuclear wave-functions, and by using a complex enough approximation of the spectral function (non-diagonal for the coherent and diagonal for the incoherent channel).
  3. Shows (within uncertainties) that "exotic" mechanisms, such as dynamical off-shellness, are not needed to describe the existing data.

Weaknesses

None except for linguistic issues (see below).

Report

The report focuses on the DVCS process on He4, a scalar/isoscalar nucleus ideal for both experimental and theoretical studies. The motivational background is the description of the process dynamics in terms of the GPDs and the corresponding 3d mapping of the target's parton content. The Authors were able to exploit the Impulse Approximation to assess the validity of the handbag diagram for the coherent process and the sufficiency of the DVCS-Bethe-Heitler interference to investigate the incoherent process, and found remarkable agreement with the recent experimental results from JLab. The contribution, therefore, is a valuable addition to our understanding of the DVCS processes at JLab energies, and is a welcome ingredient in planning future high-luminostity, high-precision experiments. This contribution certainly deserves to be published in these Proceedings.

Requested changes

Spell check.
Fix typos (for example "In facts" -> "In fact", several times; line 6 of Sec. 2: "considered" -> "neglected"?, etc.)

  • validity: high
  • significance: high
  • originality: high
  • clarity: high
  • formatting: excellent
  • grammar: good

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