Speaker
Description
Two processes contribute to the $ep \rightarrow e' p' \gamma'$ reaction: Deeply Virtual Compton Scattering, where the photon is produced at the proton vertex, and the Bether-Heitler process, where the photon is radiated from the electron. A major hurdle in the extraction of Generalised Form Factors (GPDs) from experiment arises due to the presence of two Inverse problems: a first one for the extraction of the various Compton form factors (CFFs) from data, and a subsequent one concerning the extraction of GPDs from CFFs. Here we aim to address the first inverse problem. A maximum likelihood analysis for deeply virtual exclusive photoproduction off a proton target is presented based on MCMC sampling. We provide and use a method which derives a joint likelihood of the CFFs, parameterizing the deeply virtual Compton scattering amplitude in QCD, for each observed combination of the kinematic variables defining the reaction. The likelihood for the unpolarized cross section at twist-two fully constrains only three of the CFFs.
