Beam normal spin asymmetry for the $ep\to e\Delta (1232)$ process

Abstract

We calculate the single spin asymmetry for the $ep\to e\Delta (1232)$ process, for an electron beam polarized normal to the scattering plane. Such single spin asymmetries vanish in the one-photon exchange approximation, and are directly proportional to the absorptive part of a two-photon exchange amplitude. As the intermediate state in such two-photon exchange process is on its mass shell, the asymmetry allows one to access for the first time the on-shell $\Delta \to \Delta$ as well as $N^{\ast }\to \Delta$ electromagnetic transitions. We present the general formalism to describe the $ep\to e\Delta$ beam normal spin asymmetry, and provide a numerical estimate of its value using the nucleon, $\Delta (1232)$, $S_{11}(1535)$, and $D_{13}(1520)$ intermediate states. We compare our results with the first data from the Qweak@JLab experiment and give predictions for the A4@MAMI experiment.

18 pages, 9 figures

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• Magnetic moment of the Delta(1232)-resonance in chiral effective field theory
• Baryon Magnetic Moments in the 1/N Expansion
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• Baryon Charge Radii and Quadrupole Moments in the 1/N_c Expansion: The 3-Flavor Case
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• Signatures of chiral dynamics in the Nucleon to Delta transition
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• Magnetic dipole moment of the ${\Delta }^{+}$(1232) from the $\gamma p\to \gamma {\pi }^{0}p$ reaction
• Chiral effective-field theory in the Delta(1232) region: II. radiative pion photoproduction
• Large N_c, Constituent Quarks, and N, Delta Charge Radii
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• Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering
• Decays of l=1 Baryons to Delta gamma
• Complete Analysis of Baryon Magnetic Moments in 1/N_c
• Transverse Beam Spin Asymmetries at Backward Angles in Elastic Electron-Proton and Quasi-elastic Electron-Deuteron Scattering
• Inelastic photon scattering and the magnetic moment of the $\Delta$ (1232) resonance
• Measurement of the Target-Normal Single-Spin Asymmetry in Quasi-Elastic Scattering from the Reaction ${}^3$He${}^{\uparrow }(e,e^{\prime })$
• Unitary model for the $\gamma p\to \gamma {\pi }^{0}p$ reaction and the magnetic dipole moment of the ${\Delta }^{+}(1232)$
• Chiral symmetry and the axial nucleon to Delta(1232) transition form factors
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Cited by in corpus (9)

• On-shell representations of two-body transition amplitudes: single external current
• Target-normal single-spin asymmetry in elastic electron-nucleon scattering
• Beam-normal single-spin asymmetry in elastic scattering of electrons from a spin-0 nucleus
• Measurement of the Beam-Normal Single-Spin Asymmetry for Elastic Electron Scattering from ${}^{12}$C and ${}^{27}$Al
• Two-current transition amplitudes with two-body final states
• Lepton mass effects for beam-normal single-spin asymmetry in elastic muon-proton scattering
• Parity-Violating Inelastic Electron-Proton Scattering at Low $Q^2$ Above the Resonance Region
• Target normal single-spin asymmetry in inclusive electron-nucleon scattering with two-photon exchange: Analysis using $1/N_c$ expansion
• Target normal single-spin asymmetry in inclusive electron-nucleon scattering in the 1/Nc expansion