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madgraph5 / madgraph4gpu

GPU development for the Madgraph5_aMC@NLO event generator software package
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FFS2_0 missing in HEFT gg to bb? #828

Closed valassi closed 3 months ago

valassi commented 4 months ago

Hi @oliviermattelaer I am puzzled by HEFT.

As discussed yesterday, I want to investigate a HEFT process with some phase space freedom (without pdfs).

You suggested gg > h > bb. I tried this and it has a single diagram, involving FFS2_0 (which looks new...)

But I was thinking, well this is a subset of gg > bb. I tried this, in HEFT, and I get three diagrams. These are the same three diagrams (same FFV calls) I get in the SM version of gg > bb. There are no FFS2_0 calls.

Is this not a (physics model) bug? I mean, I would have expected that the HEFT model of gg > bb contains the same SM diagrams and also additional HEFT diagrams?

Probably I am confused... Thanks! Andrea

valassi commented 3 months ago

Thanks to Olivier, this is clarified. The extra Higgs diagram is suppressed with respect to QCD and HIW <=1 is needed to generate it:

set auto_convert_model T; import model heft; generate g g > b b~ HIW<=1