Cross section of the SM double Compton process

Dear WO authors,

Recently we have simulated the Standard Model (single) Compton scattering "gamma", "e-" => "gamma", "e-" and the double Compton scattering "gamma", "e-" > "gamma", "gamma", "e-" with WO-2.7.1. The value of the double Compton scattering cross-section disagree with the results shown by Ram and Wang (1971) https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.26.476

Attached please find a plot showing this, where WO stands for Whizard. We also put (after the signature) an example of WO Sandarin script. We used the same photon energy threshold than Ram and Wand (1971): E > 5.11 keV

Thank you very much!

Best,
Igal.

PS: we also tested WO 2.8.0 for 3 different incident photon beam energies and got the same cross-section values than with WO-2.7.1.

model = SM
seed = 5257389
process ae_to_aeee_unpol_eg261keVT0 = "gamma", "e-" => "gamma","e+","e-","e-"
iterations = 8:20000,3:40000
compile
beams = "gamma", "e-"
beams_momentum = 261 keV, 0 MeV
integrate (ae_to_aeee_unpol_eg261keVT0) {cuts = all E > 5.11 keV ["gamma"]}
n_events = 10000
sample_format = lhef
simulate (ae_to_aeee_unpol_eg261keVT0)