Generating p p > c h process issue

Hi,

You need to use a model with massive c.
like
import model sm-c_mass

Cheers,

Olivier

> On 26 Sep 2021, at 15:35, lei <email address hidden> wrote:
>
> New question #698881 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/698881
>
> Dear experts,
>
> I'm interested in Higgs boson associated production with a charm quark (c + g -> c + h) and tried to generate this process using Madgraph, but it seems to not work in the first glance, while I tried the following with Madgraph 2.8.2 (and also 3.1.1):
>
> Loading default model: sm
> INFO: reload from .py file
> INFO: load particles
> INFO: load vertices
> INFO: Restrict model sm with file ../MG5_aMC_v3_1_1_py2/models/sm/restrict_default.dat .
> INFO: Run "set stdout_level DEBUG" before import for more information.
> INFO: Change particles name to pass to MG5 convention
> Defined multiparticle p = g u c d s u~ c~ d~ s~
> Defined multiparticle j = g u c d s u~ c~ d~ s~
> Defined multiparticle l+ = e+ mu+
> Defined multiparticle l- = e- mu-
> Defined multiparticle vl = ve vm vt
> Defined multiparticle vl~ = ve~ vm~ vt~
> Defined multiparticle all = g u c d s u~ c~ d~ s~ a ve vm vt e- mu- ve~ vm~ vt~ e+ mu+ t b t~ b~ z w+ h w- ta- ta+
> MG5_aMC>generate p p > c h
> INFO: Checking for minimal orders which gives processes.
> INFO: Please specify coupling orders to bypass this step.
> INFO: Trying coupling order WEIGHTED<=3: WEIGTHED IS 2*QED+QCD
> INFO: Trying process: g u > c h WEIGHTED<=4 @1
> INFO: Trying process: g c > c h WEIGHTED<=4 @1
> Command "generate p p > c h" interrupted with error:
> NoDiagramException : No amplitudes generated from process Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > c h WEIGHTED=4 @1. Please enter a valid process
>
> The error keeps occuring saying no amplitudes generated. But in fact the s-channel and t-channel disgrams are supposed to be generated.
>
> However, if the Higgs boson is replaced with a Z boson, i.e. generate p p > c Z, then the two digrams can be successfully generated.
>
> It's this issue related to the width of Higgs boson being so narrow? And if so/not, how can I get my desired result?
>
> Best regards!
>
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