Facing problem in 2-> 4 process

Respected Sir,
 I am facing problem in 2 -> 4 processes. I am using the process, u D -> u D H H in the inert doublet model, H is the dark matter. I took a benchmark point MH=65 GeV, MA=75 GeV and MH+=80 GeV, I am trying to check only the single diagram like,
     u D -> H H+ , H+ -> H W+, W+ -> u D
I have deleted all the diagram, propagate through h, A, Z, u etc. I got the cross section 0.037 fb with E1=E2=6500 GeV, pdf=cteq6l.

 But in 2-> 2, u D -> H H+ the cross section is 362 fb and the Branching ratio of H+ -> H u D is 0.32, so total cross section should be ~115 fb for this process.

I didn't understand why in 2 -> 4 process, I got 0.037 fb instead of ~115 fb;

NB: In 2 -> 4 processes I have set cut Pt>10 GeV and rapidity -5 to 5

Is there anything wrong in this process? or I missed something? Please clarify.

Sorry, I see status "Expired". It seems I have lost this request. I'll
try to answer during weekend.
Best
    Sasha

On 06/03/2016 12:37 PM, Najimuddin Khan wrote:
> Question #293927 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/293927
>
> Status: Expired => Open
>
> Najimuddin Khan is still having a problem:
> Respected Sir,
> I am facing problem in 2 -> 4 processes. I am using the process, u D -> u D H H in the inert doublet model, H is the dark matter. I took a benchmark point MH=65 GeV, MA=75 GeV and MH+=80 GeV, I am trying to check only the single diagram like,
> u D -> H H+ , H+ -> H W+, W+ -> u D
> I have deleted all the diagram, propagate through h, A, Z, u etc. I got the cross section 0.037 fb with E1=E2=6500 GeV, pdf=cteq6l.
>
> But in 2-> 2, u D -> H H+ the cross section is 362 fb and the Branching
> ratio of H+ -> H u D is 0.32, so total cross section should be ~115 fb
> for this process.
>
> I didn't understand why in 2 -> 4 process, I got 0.037 fb instead of
> ~115 fb;
>
> NB: In 2 -> 4 processes I have set cut Pt>10 GeV and rapidity -5 to 5
>
> Is there anything wrong in this process? or I missed something? Please
> clarify.
>

Sorry for so long delay.
Here key point is regularization of matrix element.
For parameters (designations of IDM implemented in micrOMEGAs)
MHX=65
MH3=75
MHC=80
laL=0.01
la2=0.01
I have
Br(~H+ -> u,D,~X)=0.336
cs ( u,D-> ~X,~H+, Pcm=6500, pdf=cteq6l1) =0.346 pb
Then for 2->4 process u,D-> ~X, (~H+-> W+,u,D) we expect 0.116 pb

2->4 calculation gives me 0.117. So, there is a good agreement

For 2->4 I use ( set via Phase space mapping menu)
=========================================
#Kinematical_scheme
12 -> 34 , 56
34 -> 3 , 4
56 -> 5 , 6

#Regularization
*** Table ***
  Regularization
  Momentum |> Mass <|> Width <| Power|
34 |MW |wW |2 |
345 |MHC |wHC |2 |
346 |MHC |wHC |2 |
=========================================

I see, I have to impelement a tool for automatic set of kinematics and
regularization to avoid problems/questions like your one.
I'll try to do it next week.

Best

      Alexander Pukhov

On 06/03/2016 12:37 PM, Najimuddin Khan wrote:
> Question #293927 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/293927
>
> Status: Expired => Open
>
> Najimuddin Khan is still having a problem:
> Respected Sir,
> I am facing problem in 2 -> 4 processes. I am using the process, u D -> u D H H in the inert doublet model, H is the dark matter. I took a benchmark point MH=65 GeV, MA=75 GeV and MH+=80 GeV, I am trying to check only the single diagram like,
> u D -> H H+ , H+ -> H W+, W+ -> u D
> I have deleted all the diagram, propagate through h, A, Z, u etc. I got the cross section 0.037 fb with E1=E2=6500 GeV, pdf=cteq6l.
>
> But in 2-> 2, u D -> H H+ the cross section is 362 fb and the Branching
> ratio of H+ -> H u D is 0.32, so total cross section should be ~115 fb
> for this process.
>
> I didn't understand why in 2 -> 4 process, I got 0.037 fb instead of
> ~115 fb;
>
> NB: In 2 -> 4 processes I have set cut Pt>10 GeV and rapidity -5 to 5
>
> Is there anything wrong in this process? or I missed something? Please
> clarify.
>

Thank You very much.

On Sat, Jun 11, 2016 at 5:37 PM, Alexander Pukhov <
<email address hidden>> wrote:

> Your question #293927 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/293927
>
> Alexander Pukhov proposed the following answer:
> Sorry for so long delay.
> Here key point is regularization of matrix element.
> For parameters (designations of IDM implemented in micrOMEGAs)
> MHX=65
> MH3=75
> MHC=80
> laL=0.01
> la2=0.01
> I have
> Br(~H+ -> u,D,~X)=0.336
> cs ( u,D-> ~X,~H+, Pcm=6500, pdf=cteq6l1) =0.346 pb
> Then for 2->4 process u,D-> ~X, (~H+-> W+,u,D) we expect 0.116 pb
>
> 2->4 calculation gives me 0.117. So, there is a good agreement
>
> For 2->4 I use ( set via Phase space mapping menu)
> =========================================
> #Kinematical_scheme
> 12 -> 34 , 56
> 34 -> 3 , 4
> 56 -> 5 , 6
>
> #Regularization
> *** Table ***
> Regularization
> Momentum |> Mass <|> Width <| Power|
> 34 |MW |wW |2 |
> 345 |MHC |wHC |2 |
> 346 |MHC |wHC |2 |
> =========================================
>
> I see, I have to impelement a tool for automatic set of kinematics and
> regularization to avoid problems/questions like your one.
> I'll try to do it next week.
>
> Best
>
> Alexander Pukhov
>
>
>
>
>
>
> On 06/03/2016 12:37 PM, Najimuddin Khan wrote:
> > Question #293927 on CalcHEP changed:
> > https://answers.launchpad.net/calchep/+question/293927
> >
> > Status: Expired => Open
> >
> > Najimuddin Khan is still having a problem:
> > Respected Sir,
> > I am facing problem in 2 -> 4 processes. I am using the process, u D
> -> u D H H in the inert doublet model, H is the dark matter. I took a
> benchmark point MH=65 GeV, MA=75 GeV and MH+=80 GeV, I am trying to check
> only the single diagram like,
> > u D -> H H+ , H+ -> H W+, W+ -> u D
> > I have deleted all the diagram, propagate through h, A, Z, u etc. I got
> the cross section 0.037 fb with E1=E2=6500 GeV, pdf=cteq6l.
> >
> > But in 2-> 2, u D -> H H+ the cross section is 362 fb and the Branching
> > ratio of H+ -> H u D is 0.32, so total cross section should be ~115 fb
> > for this process.
> >
> > I didn't understand why in 2 -> 4 process, I got 0.037 fb instead of
> > ~115 fb;
> >
> > NB: In 2 -> 4 processes I have set cut Pt>10 GeV and rapidity -5 to 5
> >
> > Is there anything wrong in this process? or I missed something? Please
> > clarify.
> >
>
> --
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>
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>
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>

--
From
Najimuddin Khan
PhD Student
IIT Indore,
Khandwa Road,
Madhya Pradesh,
India-452017

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