Benchmarks for a Global Extraction of Information from Deeply Virtual Exclusive Scattering

Almaeen, Manal; Grigsby, Jake; Hoskins, J. R.; Kriesten, Brandon; Li, Yaohang; Lin, Huey-Wen; Liuti, Simonetta

doi:10.48550/arxiv.2207.10766

Cited by 1 publication

(1 citation statement)

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“…( 4)-( 8) [16,[40][41][42]. The first step in this procedure is to obtain the CFFs from DVCS data, which at leading twist is a closed problem [18] and several leading-twist CFF extractions have been reported in the literature [43][44][45][46][47][48]. The challenge of extracting GPDs from the CFFs lies in the fact that the 𝑥 dependence of the GPDs is completely integrated out and does not appear in the CFFs.…”

Section: Cffs Gpds and Sgpdsmentioning

confidence: 99%

Shedding light on shadow generalized parton distributions

Moffat¹,

Freese²,

Cloët³

et al. 2023

Preprint

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The feasibility of extracting generalized parton distributions (GPDs) from deeply-virtual Compton scattering (DVCS) data has recently been questioned because of the existence of an infinite set of so-called "shadow GPDs" (SGPDs). These SGPDs depend on the process and manifest as multiple solutions (at a fixed scale 𝑄 2 ) to the inverse problem that needs to be solved to infer GPDs from DVCS data. SGPDs therefore pose a significant challenge for extracting GPDs from DVCS data. With this motivation we study the extent to which QCD evolution can provide constraints on SGPDs. This is possible because the known classes of SGPDs begin to contribute to observables after evolution, and can then be constrained (at the input scale 𝑄 2 0 ) by data that has a finite 𝑄 2 range. The impact that SGPDs could have on determining the total angular momentum, pressure and sheer force distributions, and tomography is also discussed. Our key finding is that scale evolution, coupled with data over a wide range of skewness 𝜉 and 𝑄 2 , can constrain the class of SGPDs that we studied and potentially make possible the extraction of GPDs from DVCS data over a limited range in the GPD variables.

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