MadGraph5_aMC@NLO

Auto width calculation

Asked by Anthony DiFranzo

Hi everyone,

I am trying to get MadGraph/MadEvent (I am using version 1.5.9) to automatically recalculate the width of certain particles in my user model whenever I go to calculate a cross-section. I'm having a hard time finding documentation on how to use this, but I have found some things through the answers/bug forums....

So I've tried a few different things. But to my understanding I should be able to enter my width value in my parameter card as Auto and then when I generate a process it will also calculate these widths. Then when I run the command "./generate_events -f" or "./generate_events default-mg5-processes-autowidth" I get the following error:

Command "generate_events -f" interrupted with error:
InvalidCmd : The UFO model does not include widths information. Impossible to compute widths automatically

Do I need to also change the values in my UFO file as well? I reevaluated my UFO file via FeynRules with Auto as the width value and but Madgraph gave me an error when I tried to generate a new process....

Does anyone have any ideas as to what I am not doing correctly? Or if anyone has some documentation on how to use autowidth, that would be super helpful!

Thanks for the help!
Anthony

If it helps my log file contains the following:

Traceback (most recent call last):
  File "/home/difraa/MadGraph5_v1_5_6/SimpDMMajorana/bin/internal/extended_cmd.py", line 819, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/home/difraa/MadGraph5_v1_5_6/SimpDMMajorana/bin/internal/extended_cmd.py", line 812, in onecmd_orig
    return func(arg, **opt)
  File "/home/difraa/MadGraph5_v1_5_6/SimpDMMajorana/bin/internal/madevent_interface.py", line 2208, in do_generate_events
    self.ask_run_configuration(mode)
  File "/home/difraa/MadGraph5_v1_5_6/SimpDMMajorana/bin/internal/madevent_interface.py", line 4310, in ask_run_configuration
    self.check_param_card(pjoin(self.me_dir,'Cards','param_card.dat' ))
  File "/home/difraa/MadGraph5_v1_5_6/SimpDMMajorana/bin/internal/madevent_interface.py", line 4646, in check_param_card
    self.do_compute_widths('%s %s' % (' '.join(pdg), path))
  File "/home/difraa/MadGraph5_v1_5_6/SimpDMMajorana/bin/internal/madevent_interface.py", line 2803, in do_compute_widths
    args = self.check_compute_widths(args)
  File "/home/difraa/MadGraph5_v1_5_6/SimpDMMajorana/bin/internal/madevent_interface.py", line 961, in check_compute_widths
    raise self.InvalidCmd, 'The UFO model does not include widths information. Impossible to compute widths automatically'

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Anthony DiFranzo
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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi Anthony,

In order to be able to generate UFO model supporting the automatic evaluation of the width,
you need to use Feynrules version 7.
This version is not public, and you need to send an email to the FR author in order to have access to it.

Cheers,

Olivier

Revision history for this message
Anthony DiFranzo (adifranz) said : 		#2

Thanks for the quick reply, Olivier!

Feynrules aside, do you know what I did wrong on the Madgraph side? It seemed like I should be able to change the width value to Auto and that would automatically calculate the width when I go to calculate a process. Is that right or am I missing something (besides the newer version of Feynrules)?

Thanks!

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#3

Hi Anthony,

> Feynrules aside, do you know what I did wrong on the Madgraph side?

You try to use to special value "Auto" for a model which didn't support this function.
So expect this, everything seems fine.

Cheers,

Olivier

Revision history for this message
Anthony DiFranzo (adifranz) said : 		#4

Alright, thank you Olivier :)
I really appreciate the help!