Unreliable results for pp->H+gamma
I wanted to explore the possibility of using H+gamma as a probe of the light Yukawa couplings. W+H / W-H is sometimes proposed and I thought H+gamma might be cleaner. The trivial LO Run.dat I am using is attached.Run.dat
It is very simple - declare the up quark massive and then set its Yukawa. However, if I request the process 93 93 -> 25 22 I get "No hard process found". I work around this by having a set of processes 2 -2 -> 25 22 and the charge conjugate (and all the other light quarks for good measure.) This generates 4 Feynman diagrams, with a quark annihilation and the bosons radiated off, and produces a cross-section for me. This does seem to represent a problem in the ME generation?
I put a pt cut of 150 GeV on the Higgs to imagine a trigger on the photon. H+gamma is compared to other H+V in this plot:
The resulting dependence of the H+gamma cross-section on the Yukawa has a strange wiggle - I would have expected a smooth rise as (unlike VH) there are no other interfering processes. All 4 diagrams feature one uuH coupling. Perhaps I am just being dumb, but this seems wrong to me. Bill PS Sherpa version 2.2.15 (Cho Oyu) on alma 9