MadGraph5_aMC@NLO

problem with event generation for UFO

Asked by nabanita ganguly

Hi MG5 team,

I have generated a model file in UFO format using Feynrule. When I import the model inside mg5, it worked fine. processes are being generated as per expectation. The problem arises when I give the command "output". I am getting the following error messages :

MG5_aMC>output
INFO: initialize a new directory: PROC_NMUED_UFO_3
INFO: remove old information in PROC_NMUED_UFO_3
INFO: Organizing processes into subprocess groups
INFO: Generating Helas calls for process: u u~ > w1+ w1- WEIGHTED<=2 @1
INFO: Processing color information for process: u u~ > w1+ w1- @1
INFO: Generating Helas calls for process: c c~ > w1+ w1- WEIGHTED<=2 @1
INFO: Processing color information for process: c c~ > w1+ w1- @1
INFO: Generating Helas calls for process: d d~ > w1+ w1- WEIGHTED<=2 @1
INFO: Processing color information for process: d d~ > w1+ w1- @1
INFO: Generating Helas calls for process: s s~ > w1+ w1- WEIGHTED<=2 @1
INFO: Processing color information for process: s s~ > w1+ w1- @1
INFO: Creating files in directory P1_uux_w1pw1m
INFO: Generating Feynman diagrams for Process: u u~ > w1+ w1- WEIGHTED<=2 @1
INFO: Finding symmetric diagrams for subprocess group uux_w1pw1m
INFO: Creating files in directory P1_ccx_w1pw1m
INFO: Generating Feynman diagrams for Process: c c~ > w1+ w1- WEIGHTED<=2 @1
INFO: Finding symmetric diagrams for subprocess group ccx_w1pw1m
INFO: Creating files in directory P1_ddx_w1pw1m
INFO: Generating Feynman diagrams for Process: d d~ > w1+ w1- WEIGHTED<=2 @1
INFO: Finding symmetric diagrams for subprocess group ddx_w1pw1m
INFO: Creating files in directory P1_ssx_w1pw1m
INFO: Generating Feynman diagrams for Process: s s~ > w1+ w1- WEIGHTED<=2 @1
INFO: Finding symmetric diagrams for subprocess group ssx_w1pw1m
Generated helas calls for 4 subprocesses (8 diagrams) in 0.017 s
Wrote files for 32 helas calls in 0.156 s
Export UFO model to MG4 format
Command "output " interrupted in sub-command:
"output" with error:
ZeroDivisionError : complex division by zero
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in 'MG5_debug'.
Please attach this file to your report.

Could you please help me to understand what exactly is going wrong.

Regards,
Nabanita

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Last query:
Last reply:
Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

With neither the debug file, nor the model difficult to really comment.
The likely situation is that some lorentz structure are not correctly defined and lead to a division by zero.
i.e. if your lorentz structure is something like
1/(M(1)**2 - M(1)**2)
then this will be simplified to 1/0 and create the above error.

Cheers,

Olivier

Can you help with this problem?

Provide an answer of your own, or ask nabanita ganguly for more information if necessary.

To post a message you must log in.