Filter quarks for n+1-particle processes

Hi Christian,
i am not sure what you ask is possible, because you need all flavours and splittings in order to cancel the poles of the virtual matrix elements...
what do you need to do exactly?

Let me know,

Marco

Hi Marco,

I want to compare Madgraph with my own calculation, which, so far, can only deal with one quark-type, e.g. up-quarks. Of course, in the virtual matrix elements also only up-quarks occur. The sum of virtual and real ME should be finite.

In principle, I can achieve this by creating a model which is the SM with only one quark. But I wonder if there is a simpler way.

Greetings,
Christian

Ciao Christian,
i think that creating a model with only one quark is the best option, as in
this case you can use the rest of the code as it is without changing things
(and therefore introducing possible extra bugs...
Do you know how to do this?

Cheers,

Marco

Marco Zaro

On Mon, Nov 3, 2014 at 3:51 PM, CWeiss <<email address hidden>
> wrote:

> Question #256709 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/256709
>
> CWeiss gave more information on the question:
> Hi Marco,
>
> I want to compare Madgraph with my own calculation, which, so far, can
> only deal with one quark-type, e.g. up-quarks. Of course, in the virtual
> matrix elements also only up-quarks occur. The sum of virtual and real
> ME should be finite.
>
> In principle, I can achieve this by creating a model which is the SM
> with only one quark. But I wonder if there is a simpler way.
>
> Greetings,
> Christian
>
> --
> You received this question notification because you are a direct
> subscriber of the question.
>

No, not yet. Maybe you could briefly outline it?

Thanks a lot for your help!
Christian

ok, so, start from the loop_sm inside models;
1) copy the directory
cp loop_sm my-loop_sm

2) inside particles.py remove the other quarks

3) inside vertices.py remove the interactions where the other quarks enter

4) inside CT_vertices.py remove the interactions where the other quarks enter as ‘particles’ and remove the other quarks from the ‘loop_particles’ entry

you should be able to load the model with

./import my-loop_sm

Cheers,

MArco

On 03 Nov 2014, at 16:06, CWeiss <email address hidden> wrote:

> Question #256709 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/256709
>
> CWeiss posted a new comment:
> No, not yet. Maybe you could briefly outline it?
>
> Thanks a lot for your help!
> Christian
>
> --
> You received this question notification because you are a direct
> subscriber of the question.

Hi,

I did as you proposed, however, there is one thing I just cannot figure out.

When importing the model I got the message that particle "b" was not known, and indeed I still had

b.loop_particles = [[[5,21]]]
b.counterterm = {(1,0,0):CTParam.bWcft_UV.value}

in particles.py. This part of the code corresponds to wave function renormaliztion. So, I erased it as well as the corresponding lines. I further removed the following line corresponding to gluon wave function renormalization, because it depends on functions of charme, bottom and top quantities. Upon generating the process, i get

IndexError : list index out of range

So far, I could not figure out where this error comes from. Do you have any idea?

Greetings,
Christian