Double deeply virtual Compton scattering with positron beams at SoLID

Abstract

Double Deeply Virtual Compton Scattering (DDVCS) is the only experimental channel for the determination of the dependence of the Generalized Parton Distributions (GPDs) on both the average and the transferred momentum independently. The physics observables of the electron induced di-muon production reaction #» e ± p → e ± pµ + µ − off unpolarized hydrogen are discussed. Their measurement with the high luminosity and large acceptance SoLID spectrometer at the Thomas Jefferson National Accelerator Facility, using polarized and unpolarized positron and electron beams at 11 GeV is investigated. This experimental configuration is shown to provide unprecedented access to the GPDs with the determination of the real and imaginary parts of the Compton Form Factor H in an unexplored phase space, and to enable an exploratory investigation of higher twist effects.

An experimental program with high duty-cycle polarized and unpolarized positron beams at Jefferson Lab

“…Complementing CLAS12 with the ALERT low energy recoil tracker [142] will permit the investigation of coherent and incoherent DVCS off nuclei [143], pro-viding a novel method to look at nuclear forces and modifications of the nucleon structure through the real part of the CFFs. The addition of a muon detector to the SoLID spectrometer would enable measurements of polarized electron and positron beams DDVCS cross sections, giving a direct access to the real and imaginary parts of the CFF H(ξ , ξ, t) related to the GPD out-of the diagonals x=±ξ [144].…”