First Exclusive Measurement of Deeply Virtual Compton Scattering off ${}^4$He: Toward the 3D Tomography of Nuclei

Abstract

We report on the first measurement of the beam-spin asymmetry in the exclusive process of coherent deeply virtual Compton scattering off a nucleus. The experiment used the 6 GeV electron beam from the CEBAF accelerator at Jefferson Lab incident on a pressurized ${}^4$He gaseous target placed in front of the CEBAF Large Acceptance Spectrometer (CLAS). The scattered electron was detected by CLAS and the photon by a dedicated electromagnetic calorimeter at forward angles. To ensure the exclusivity of the process, a specially designed radial time projection chamber was used to detect the recoiling ${}^4$He nuclei. We measured beam-spin asymmetries larger than those observed on the free proton in the same kinematic domain. From these, we were able to extract, in a model-independent way, the real and imaginary parts of the only ${}^4$He Compton form factor, ${\mathcal{H}}_{\mathcal{A}}$. This first measurement of coherent deeply virtual Compton scattering on the ${}^4$He nucleus, with a fully exclusive final state via nuclear recoil tagging, leads the way toward 3D imaging of the partonic structure of nuclei.

References in corpus (52)

• Gauge-Invariant Decomposition of Nucleon Spin and Its Spin-Off
• Wave Functions, Evolution Equations and Evolution Kernels from Light-Ray Operators of QCD
• Generalized Parton Distributions
• Deeply Virtual Compton Scattering
• Nonforward Parton Distributions
• Unraveling hadron structure with generalized parton distributions
• Hard Exclusive Reactions and the Structure of Hadrons
• Impact Parameter Dependent Parton Distributions and Off-Forward Parton Distributions for $\zeta \to 0$
• Scaling Limit of Deeply Virtual Compton Scattering
• Theory of deeply virtual Compton scattering on the nucleon
• Generalized parton distributions in impact parameter space
• Deeply virtual electroproduction of photons and mesons on the nucleon : leading order amplitudes and power corrections
• Measurement of the Beam-Spin Azimuthal Asymmetry Associated with Deeply-Virtual Compton Scattering
• Nucleon Form Factors from Generalized Parton Distributions
• Proof of Factorization for Deeply Virtual Compton Scattering in QCD
• Observation of exclusive DVCS in polarized electron beam asymmetry measurements
• One-Loop Corrections and All Order Factorization In Deeply Virtual Compton Scattering
• Generalized Parton Distributions in the valence region from Deeply Virtual Compton Scattering
• New measurements of the EMC effect in very light nuclei
• Measurement of deeply virtual Compton scattering at HERA
• Deeply Virtual Compton Scattering Beam-Spin Asymmetries
• Measurement of Deeply Virtual Compton Scattering at HERA
• Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering
• Evolution and models for skewed parton distributions
• Deeply Virtual Compton Scattering off the neutron
• Transverse Deformation of Parton Distributions and Transversity Decomposition of Angular Momentum
• Generalized parton distributions in the deuteron
• Measurement of Deeply Virtual Compton Scattering with a Polarized Proton Target
• Cross sections for the exclusive photon electroproduction on the proton and Generalized Parton Distributions
• The Beam--Charge Azimuthal Asymmetry and Deeply Virtual Compton Scattering
• The E00-110 experiment in Jefferson Lab's Hall A: Deeply Virtual Compton Scattering off the Proton at 6 GeV
• Beam-helicity and beam-charge asymmetries associated with deeply virtual Compton scattering on the unpolarised proton
• Measurement of Deeply Virtual Compton Scattering at HERA
• Measurement of Azimuthal Asymmetries With Respect To Both Beam Charge and Transverse Target Polarization in Exclusive Electroproduction of Real Photons
• Deep Electroproduction of Photons and Mesons on the Deuteron
• Deeply virtual Compton scattering off nuclei
• Nucleon hologram with exclusive leptoproduction
• Measurement of double-spin asymmetries associated with deeply virtual Compton scattering on a transversely polarized hydrogen target
• Exclusive Leptoproduction of Real Photons on a Longitudinally Polarised Hydrogen Target
• Beam-helicity asymmetry arising from deeply virtual Compton scattering measured with kinematically complete event reconstruction
• Single and double spin asymmetries for deeply virtual Compton scattering measured with CLAS and a longitudinally polarized proton target
• Interpretation of the Flavor Dependence of Nucleon Form Factors in a Generalized Parton Distribution Model
• DVCS on spinless nuclear targets in impulse approximation
• Separation of contributions from deeply virtual Compton scattering and its interference with the Bethe--Heitler process in measurements on a hydrogen target
• Longitudinal target-spin asymmetries for deeply virtual Compton scattering
• Refined analysis of photon leptoproduction off spinless target
• The dual parameterization of the proton generalized parton distribution functions H and E and description of the DVCS cross sections and asymmetries
• On the A-dependence of nuclear generalized parton distributions
• Microscopic Description of Deeply Virtual Compton Scattering off Spin-0 Nuclei
• Nuclear-mass dependence of azimuthal beam-helicity and beam-charge asymmetries in deeply virtual Compton scattering
• 3D Structure and Nuclear Targets
• Neutron contribution to nuclear DVCS asymmetries

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• Hadrons and Nuclei
• The Present and Future of QCD
• D-term and structure of point-like and composed spin-0 particles
• Exposing Novel Quark and Gluon Effects in Nuclei
• The dynamic origins of fermionic D-terms
• Exploring the Structure of the Bound Proton with Deeply Virtual Compton Scattering
• Transition distribution amplitudes and hard exclusive reactions with baryon number transfer
• 2D energy-momentum tensor distributions of nucleon in a large-$N_c$ quark model from ultra-relativistic to non-relativistic limit
• Coherent deeply virtual Compton scattering off ${}^4$He
• Prospects for quarkonium studies at the high-luminosity LHC
• Measurement of deeply virtual Compton scattering off Helium-4 with CLAS at Jefferson Lab
• Single-Transverse-Spin Asymmetries in Exclusive Photo-production of J/psi in Ultra-Peripheral Collisions in the Fixed-Target Mode at the LHC and in the Collider Mode at RHIC
• Catching a glimpse of the parton structure of the bound proton
• Incoherent deeply virtual Compton scattering off ${}^4$He
• Spin-orbit correlation and spatial distributions for spin-0 hadrons
• Deeply virtual Compton scattering off Helium nuclei with positron beams
• Beam Spin Asymmetry in Electroproduction of Pseudoscalar or Scalar Meson Production off the Scalar Target
• Generalized parton distributions of light nuclei
• Unified and optimal frame choice for generalized parton distributions
• Analysis of virtual meson production in solvable (1+1) dimensional scalar field theory
• Deeply virtual Compton Scattering off ${}^4$He
• New framework for extracting GPDs from exclusive photon electroproduction