skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Deeply virtual Compton scattering at Jefferson Laboratory

Abstract

The generalized parton distributions (GPDs) have emerged as a universal tool to describe hadrons in terms of their elementary constituents, the quarks and the gluons. Deeply virtual Compton scattering (DVCS) on a proton or neutron ($N$), $$e N \rightarrow e' N' \gamma$$, is the process more directly interpretable in terms of GPDs. The amplitudes of DVCS and Bethe-Heitler, the process where a photon is emitted by either the incident or scattered electron, can be accessed via cross-section measurements or exploiting their interference which gives rise to spin asymmetries. Spin asymmetries, cross sections and cross-section differences can be connected to different combinations of the four leading-twist GPDs ($${H}$$, $${E}$$, $${\tilde{H}}$$, $${\tilde{E}}$$) for each quark flavors, depending on the observable and on the type of target. This paper gives an overview of recent experimental results obtained for DVCS at Jefferson Laboratory in the halls A and B. Several experiments have been done extracting DVCS observables over large kinematics regions. Multiple measurements with overlapping kinematic regions allow to perform a quasi-model independent extraction of the Compton form factors, which are GPDs integrals, revealing a 3D image of the nucleon.

Authors:
 [1]
  1. Fairfield University - Department of Physics 1073 North Benson Road, Fairfield, CT 06430, USA; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1332086
Report Number(s):
JLAB-PHY-15-2152; DOE/OR/23177-3991; arXiv:1510.04558
DOE Contract Number:
AC05-06OR23177
Resource Type:
Conference
Resource Relation:
Conference: CIPANP 2015, Vail, CO (United States), 19-24 May 2015
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Biselli, Angela S. Deeply virtual Compton scattering at Jefferson Laboratory. United States: N. p., 2016. Web.
Biselli, Angela S. Deeply virtual Compton scattering at Jefferson Laboratory. United States.
Biselli, Angela S. 2016. "Deeply virtual Compton scattering at Jefferson Laboratory". United States. doi:. https://www.osti.gov/servlets/purl/1332086.
@article{osti_1332086,
title = {Deeply virtual Compton scattering at Jefferson Laboratory},
author = {Biselli, Angela S.},
abstractNote = {The generalized parton distributions (GPDs) have emerged as a universal tool to describe hadrons in terms of their elementary constituents, the quarks and the gluons. Deeply virtual Compton scattering (DVCS) on a proton or neutron ($N$), $e N \rightarrow e' N' \gamma$, is the process more directly interpretable in terms of GPDs. The amplitudes of DVCS and Bethe-Heitler, the process where a photon is emitted by either the incident or scattered electron, can be accessed via cross-section measurements or exploiting their interference which gives rise to spin asymmetries. Spin asymmetries, cross sections and cross-section differences can be connected to different combinations of the four leading-twist GPDs (${H}$, ${E}$, ${\tilde{H}}$, ${\tilde{E}}$) for each quark flavors, depending on the observable and on the type of target. This paper gives an overview of recent experimental results obtained for DVCS at Jefferson Laboratory in the halls A and B. Several experiments have been done extracting DVCS observables over large kinematics regions. Multiple measurements with overlapping kinematic regions allow to perform a quasi-model independent extraction of the Compton form factors, which are GPDs integrals, revealing a 3D image of the nucleon.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 8
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • After about 10 years of growing interest for Generalized Parton Distributions come the first results from dedicated experiments, using the golden Deeply Virtual Compton Scattering process. After a short introduction, we will explain the experimental methodology and show results of the Hall A E00-110 experiment, which aimed at measuring helicity-dependent photon electroproduction cross sections. We will emphasize how this experiment provided the first stringent tests of the scaling property of this process, allowing for the first time a model-independent extraction of a linear combination of Generalized Parton Distributions. We will also describe the Hall B E01-113 experiment which measured themore » photon electroproduction beam spin asymmetry over a wide kinematical range. The summary will include an outlook on the next generation of experiments which are already planned at Jefferson Lab at 6 GeV, but also after the planned 12 GeV upgrade.« less
  • Recent results from the Deeply Virtual Compton Scattering (DVCS) program at Jefferson Lab will be presented.Approved dedicated DVCS experiments at 6 GeV will be discussed.
  • The Generalized Parton Distribution framework was introduced in the late 90’s and describes the nucleon in a revolutionary way, correlating the information from both momentum and transverse position space into experimentally accessible functions. After a brief introduction, this article reviews the Jefferson Lab 6 GeV measurements of Deeply Virtual Compton Scattering in Halls A and B, which give a unique access to Generalized Parton Distributions (GPD). The second part of this article reviews the Jefferson Lab 12 GeV upgrade in general terms, and then focuses on the GPD program in Halls A and B.
  • Generalized Parton Distributions (GPDs) are universal functions which provide a comprehensive description of hadron properties in terms of quarks and gluons. Deeply Virtual Compton Scattering (DVCS) is the simplest hard exclusive process involving GPDs. In particular, the DVCS on the neutron is mostly sensitive to E, the less constrained GPD, wich allows to access to the quark angular momentum. The first dedicated DVCS experiment on the neutron ran in the Hall A of Jefferson Lab in fall 2004. The high luminosity of the experiment and the resulting background rate recquired specific devices which are decribed in this document. The analysismore » methods and the experiment results, leading to preliminary constraints on the GPD E, are presented.« less
  • The exclusive leptoproduction of a real photon is considered to be the "cleanest" way to access the Generalized Parton Distribution (GPD). This process is called Deeply Virtual Compton Scattering (DVCS) lN {yields} lN{gamma} , and is sensitive to all the four GPDs. Measuring the DVCS cross section is one of the main goals of this thesis. In this thesis, we present the work performed to extract on a wide phase-space the DVCS cross-section from the JLab data at a beam energy of 6 GeV.