2015/10/06 by M. M. Dalton, Mark Macrae Dalton, Dalton, Mark Macrae
Engineering · Physics and Astronomy · #Crystallography and Radiation Phenomena #FOS: Physical sciences #Nuclear Experiment (nucl-ex) #Nuclear Physics and Applications #Particle Accelerators and Free-Electron Lasers #nucl-ex
paper · pdf · doi:10.48550/arxiv.1510.01582
Talk presented at CIPANP2015
arxiv created 2015/10/06 · openalex publication_date 2015/10/06 · arxiv updated 2015/10/07 · openalex created_date 2022/09/11 · openalex updated_date 2026/07/28
The beam-normal single-spin asymmetry, Bn, exists in the scattering of high energy electrons, polarized transverse to their direction of motion, from nuclear targets. To first order, this asymmetry is caused by the interference of the one-photon exchange amplitude with the imaginary part of the two-photon exchange amplitude. Measurements of Bn, for the production of a Δ(1232) resonance from a proton target, will soon become available from the Qweak experiment at Jefferson Lab and the A4 experiment at Mainz. The imaginary part of two-photon exchange allows only intermediate states that are on-shell, including the Δ itself. Therefore such data is sensitive to γΔΔ, the elastic form-factors of the Δ. This article will introduce the form-factors of the Δ, discuss what might be learned about the elastic form-factors from these new data, describe ongoing efforts in calculation and measurement, and outline the possibility of future measurements.