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effective hgg vertex get zero cross section

Asked by Marco Merchand

Dear Calchep experts

I implemented a new model with three Higgs doublets (two of them get vev, the other one is inert) in feynrules. Following closely the formulas for the effective hgg coupling that comes within the IDM of micromegas I wrote down the interaction as

g |g |h | |-4*Lggh*Rqcd_h |p1.p2*m1.m2-m2.p1*m1.p2

in the lagrangian file where

LggH |-cabs(hGGeven(MH, aQCD_H, 3, 1, 3, MB, x212x0/MB, 1, 3, MC, x217x0/MC, 1, 3, MT, x218x0/MT))

Rqcd_h |sqrt(1+aQCD_h*(149/12+aQCD_h*(68.6482-aQCD_h*212.447)))
The x212x0 functions are coupling hff with f the corresponding fermion.

 when I calculate the cross section g,g->h using monte carlo integration in GUI session I obtain zero cross section.

Can someone please point out to me what am I doing wrong?

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Marco Merchand
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Alexander Pukhov (pukhov) said : 		#1

Have you implemented structure function for gluon?

You can check how it works  for  SM(hgg+)  in CalcHEP distribution. You
can use the same function.

Send me your model.  [<email address hidden>]    Then I'll look why you
get zero.

Best

    Alexander Pukhov

On 23.09.2019 4:10, Marco Merchand wrote:
> New question #684125 on CalcHEP:
> https://answers.launchpad.net/calchep/+question/684125
>
> Dear Calchep experts
>
> I implemented a new model with three Higgs doublets (two of them get vev, the other one is inert) in feynrules. Following closely the formulas for the effective hgg coupling that comes within the IDM of micromegas I wrote down the interaction as
>
> g |g |h | |-4*Lggh*Rqcd_h |p1.p2*m1.m2-m2.p1*m1.p2
>
> in the lagrangian file where
>
> LggH |-cabs(hGGeven(MH, aQCD_H, 3, 1, 3, MB, x212x0/MB, 1, 3, MC, x217x0/MC, 1, 3, MT, x218x0/MT))
>
> Rqcd_h |sqrt(1+aQCD_h*(149/12+aQCD_h*(68.6482-aQCD_h*212.447)))
> The x212x0 functions are coupling hff with f the corresponding fermion.
>
> when I calculate the cross section g,g->h using monte carlo integration in GUI session I obtain zero cross section.
>
> Can someone please point out to me what am I doing wrong?
>

Revision history for this message
Marco Merchand (mamerchandmedi) said : 		#2

Thanks this solved my question