"launch" with error: ValueError : String 1/4 Nc^1 T(-1002,-1001) T(-1000,-1001) cannot be simplified to a number!

Asked by Bilguun on 2018-02-01

I am implementing leptoquark model on Feynrule based on paper arXiv:hep-ph/0502067v1 . My FR file has only contain u1mu field from the paper. And i succesfully implemented the model but when i run some process on MG5 there is a error shown.
Which is saying

""launch" with error:
ValueError : String 1/4 Nc^1 T(-1002,-1001) T(-1000,-1001) cannot be simplified to a number!
"

Is anyone can help me on that where did i some mistake?

My FR code is below:

M$InteractionOrderHierarchy = {
  {NP, 8}
};

IndexRange[Index[Gluon ]] = NoUnfold[Range[8]];
IndexRange[Index[Colour ]] = NoUnfold[Range[3]];
IndexStyle[Gluon, a];
IndexStyle[Colour, m];

M$ClassesDescription = {

  V[5] == {
    ClassName -> U,
    SelfConjugate -> False,
    Indices -> {Index[Colour]},
    QuantumNumbers -> {Q -> -2/3, FermionNumber -> 0, LeptonNumber -> 1},
    Mass -> {MU, 700},
    Width -> {WU, 1},
    PropagatorLabel -> "U",
    PropagatorType -> Sine,
    PropagatorArrow -> None,
    PDG -> 6000048,
    ParticleName -> "U-",
    AntiParticleName -> "U+",
    FullName -> "U"
  }

}

M$Parameters = {

       h1 == {
               Value -> 0.1,
               InteractionOrder -> {NP, 1},
               ParameterType -> External,
               ComplexParameter -> False
              }

   };

LagU1 := (MU)^2 U[mu] HC[U[mu]] - 1/4 FS[U, mu, nu, m] FS[U, mu, nu, m] + DC[Ubar[mu, m], mu] DC[U[mu, m], mu] ;
LagFerm := h1 (vlbar[i].uq[i] - lbar[j].(1 - Ga[mu]).dq[j]) U[mu] ;
LagLepQ := LagU1 + LagFerm + HC[LagU1] + HC[LagFerm] ;

PS: Sorry for my bad english.

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
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Last query:
2018-02-05
Last reply:
2018-02-05

Hi,

I'm not able to help you at the FR level.
If you provide your UFO file, I might be able to point you what the problem is in that file.
But otherwise, you might want to contact FR author.

Just one question, does your model contains gluon? and does you particles has gluon interaction.
FR is a bit messy on particle/anti-particle color index and we use the gluon interaction to correct the UFO model if FR mess up a bit.

Cheers,

Olivier

Bilguun (bilguun7) said : #2

You can see my model UFO file from here:

https://drive.google.com/drive/folders/1yv3hajAN-8RypIy3T-IHu4A5hSq-DjiU?usp=sharing

Yes. My model contains gluon interaction. The new particles is triplet under SU(3) group. And Indices is Colour.

Last year, i implemented octet particle in FR and same kind of error appeared. But somehow disappeared. Dont know why.

Bilguun (bilguun7) said : #4

Hi,

I think i am writing this part wrong. "LagFerm := h1 (vlbar[i].uq[i] - lbar[j].(1 - Ga[mu]).dq[j]) U[mu] ;"

Tried so many times to correct but all failed. Can anyone help me on that?

Hi,

I have loaded your LeptQuark model and successfully imported the model and generated matrix-element for all 2 to 2 process.

I have also computed the cross-section for p p > j j without any issue.

I do not know FeynRules so you will not get help on how to write your FeynRules here. But since I do not reproduce your crash (probably I need to generate another process for that) I'm not even able to give you a hint where the problem can be in your Lagrangian. (But you actually seems to know that already anyway)

Cheers,

Olivier

Bilguun (bilguun7) said : #6

Hi Oliver, thanks for the reply.

I am sorry for that i forgot to mention, for p p > u1+ u1- process its okay. And u1- > ve~ t ( maybe i interchanged the notation sorry ) is alone okay. But when i tried to compute p p > u1+ u1- , ( u1- > ve~ t ) , ( u1+ > e+ b ) , the error appeared.

Hi,

I should be confused somewhere since
1) your model does not have u1+ particles (I replaced it by u+)
2) When generating your process, I have:
 Command "generate p p > u+ u- , ( u- > ve~ t ), ( u+ > e+ b )" interrupted with error:
InvalidCmd : No LeptonNumber conservation for this process

I guess that something went wrong with your google drive since it was a mess to download the model from that platform since it was not in a .tar.gz format.

Cheers,

Olivier

Bilguun (bilguun7) said : #8

Hi Olivier

I am sorry again for that confused about decay channel, i interchanged them i think.

The correct is "generate p p > u+ u- , ( u- > ve t~ ) , ( u+ > e- b~ )"

The particle u-/u+ has Q = -2/3 , LeptonNumber = 1 .

Recently, i put T[a] in the vertices then error changed to " array index out of range" .

Well,

I tried that one and it returns:

Command "generate p p > u+ u- , ( u- > ve t~ ) , ( u+ > e- b~)" interrupted with error:
InvalidCmd : No LeptonNumber conservation for this process

Cheers,

Olivier

On 2 Feb 2018, at 17:09, Bilguun <<email address hidden><mailto:<email address hidden>>> wrote:

generate p p > u+ u- , ( u- > ve t~ ) , ( u+ > e- b~
)

Bilguun (bilguun7) said : #10

Hi Olivier,

Could you try decay channel in this "u+ > ve t~ , u- > e- b~ " ?

Since i implemented this vertice uqbar.vl U[mu] but it appears different in madgraph. Sometimes i confused on this, sorry.

PS: I left my laptop on my work, and cant check things my own sorry for wasting your time.

MG5_aMC>generate u+ > ve t~
Command "generate u+ > ve t~" interrupted with error:
InvalidCmd : No LeptonNumber conservation for this process
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in 'MG5_debug'.
Please attach this file to your report.

On the other hand this one work:
MG5_aMC>generate u- > e- b~
INFO: Trying process: u- > e- b~ @1
INFO: Process has 1 diagrams
1 processes with 1 diagrams generated in 0.002 s
Total: 1 processes with 1 diagrams

Now you can see that the color information is wrong:
Interactions 16 : b~ e- u+ has the following property:
{
    'id': 16,
    'particles': [-5,11,-6000048],
    'color': [1 ],
    'lorentz': ['FFV2'],
    'couplings': {(0, 0): 'GC_16'},
    'orders': {'NP': 1},
    'loop_particles': None,
    'type': 'base',
    'perturbation_type': None
}

It is written such as this vertex does not have any color index at all.

You can compare with a u u~ vertex (you should have the same color structure apriori)
Interactions 65 : u~ u a has the following property:
{
    'id': 65,
    'particles': [-2,2,22],
    'color': [1 T(1,0)],
    'lorentz': ['FFV1'],
    'couplings': {(0, 0): 'GC_2'},
    'orders': {'QED': 1},
    'loop_particles': None,
    'type': 'base',
    'perturbation_type': None
}

Hope that this information will help you to find what the problem is in your FR implementation.

Cheers,

Olivier

On 3 Feb 2018, at 02:52, Bilguun <<email address hidden><mailto:<email address hidden>>> wrote:

u+ > ve t~ , u- > e- b~

Bilguun (bilguun7) said : #12

Hi Olivier,

Could you explain to me that where can i found that vertex?

I changed the new particles decay to lepton and quark vertices many timnes, including colour structure and representation, but any of them did not work.

Is it possible to change it by hand in UFO file?

I am just started to using MG5 and FR.

Thank you for the reply.

Hi,

I would strongly discourage to edit the UFO file, since forbids to have any trust on the model.
Also if you are just starting FR/MG5, it is much more valuable to invest time in FR in order to be able
to have it right that investing time in learning the UFO convention.

I can only suggest that you contact FeynRules author.
Additionally your model seems quite similar to the default model used in any FeynRules tutorial.
Did you check that?

Cheers,

Olivier

> On 5 Feb 2018, at 03:32, Bilguun <email address hidden> wrote:
>
> Question #663950 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/663950
>
> Status: Answered => Open
>
> Bilguun is still having a problem:
> Hi Olivier,
>
> Could you explain to me that where can i found that vertex?
>
> I changed the new particles decay to lepton and quark vertices many
> timnes, including colour structure and representation, but any of them
> did not work.
>
> Is it possible to change it by hand in UFO file?
>
> I am just started to using MG5 and FR.
>
> Thank you for the reply.
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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