MadGraph5_aMC@NLO

No amplitudes generated from process p p > g1 > t t~ (using the mued model)

Asked by M Hansen

Hi,
I used feynrules to write UFO code for the mued model. Now I try to generate a process using the UFO code in MadGraph 5 as model. I want to generate the process p p > g1 > t t~ (kaluza-klein excitation of the gluon decaying to ttbar) but it doesn't work.
for a process like p p > g > t t~ it works but in the other case I get the following error-message:

mg5>import mued
The import format was not given, so we guess it as model
INFO: load particles
INFO: load vertices
INFO: Change particles name to pass to MG5 convention
Kept definitions of multiparticles l- / j / vl / l+ / p / vl~ unchanged
Defined multiparticle all = g a ve vm vt e- ve~ vm~ vt~ e+ g1 u c t d s b su1 sc1 st1 sd1 ss1 sb1 du1 dc1 dt1 dd1 ds1 db1 u~ c~ t~ d~ s~ b~ su1~ sc1~ st1~ sd1~ ss1~ sb1~ du1~ dc1~ dt1~ dd1~ ds1~ db1~ z w+ h0 a1 z1 w1+ h1 w- w1- mu- ta- e1l- m1l- t1l- ve1 vm1 vt1 e1r- m1r- t1r- mu+ ta+ e1l+ m1l+ t1l+ ve1~ vm1~ vt1~ e1r+ m1r+ t1r+
mg5>generate p p > g1 > t t~
INFO: Checking for minimal orders which gives processes.
INFO: Please specify coupling orders to bypass this step.
INFO: Trying process: g g > g1 > t t~ WEIGHTED=2
INFO: Trying process: u u~ > g1 > t t~ WEIGHTED=2
INFO: Trying process: u c~ > g1 > t t~ WEIGHTED=2
INFO: Trying process: c u~ > g1 > t t~ WEIGHTED=2
INFO: Trying process: c c~ > g1 > t t~ WEIGHTED=2
INFO: Trying process: d d~ > g1 > t t~ WEIGHTED=2
INFO: Trying process: d s~ > g1 > t t~ WEIGHTED=2
INFO: Trying process: s d~ > g1 > t t~ WEIGHTED=2
INFO: Trying process: s s~ > g1 > t t~ WEIGHTED=2
INFO: Trying process: u~ u > g1 > t t~ WEIGHTED=2
INFO: Trying process: c~ c > g1 > t t~ WEIGHTED=2
INFO: Trying process: d~ d > g1 > t t~ WEIGHTED=2
INFO: Trying process: s~ s > g1 > t t~ WEIGHTED=2
Command "generate p p > g1 > t t~" interrupted with error:
InvalidCmd : No amplitudes generated from process Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > g1> t t~ WEIGHTED=2. Please enter a valid process

I executed python write_param_card.py before I imported the model and tried to generate the process. Do I have to do anything further? Maybe I just forgot one step...Can you help me?

Best regards,
Maike

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Johan Alwall
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Johan Alwall (johan-alwall) said : 		#1

Hello Maike,

Can you send me a tar ball with the UFO files for the model at jalwall_at_ntu.edu.tw?

Thanks,
Johan

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Best Johan Alwall (johan-alwall) said : 		#2

Hello again Maike,

It seems that this model has a K-symmetry, so the KK-states can only be produced in pairs. In particular, I don't see any G1-t-tbar coupling (only G1-t0-Dt1 coupling). So there shouldn't be any diagrams from the process you quote.

You can easily check which interactions are available in a model by doing "display interactions" inside the mg5 interface.

All the best,
Johan

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M Hansen (j-hansen-r) said : 		#3

Hi Johan,
thank you very much for the help!
Best regards,
Maike

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M Hansen (j-hansen-r) said : 		#4

Thanks Johan Alwall, that solved my question.

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Olivier Mattelaer (olivier-mattelaer) said : 		#5

Just to add even more detail:

you can do
display interactions X Y

to see all interaction which contains particles X and Y.
This is even faster than listing all interactions.

Cheers,

Olivier