decay widths calculations for mssm

Dear Juhi,

The mssm model built-tin in MadGraph works with an SLHA1 card.
This is the reason why the MadWidth (arXiv:1402.1178) programs returns a SLHA1 card for that model.

Now in most of the case, MG supports a SLHA2 input format since I have created some basic SLHA2 to SLHA1 converter for this model.
I guess that your card is in the SLHA2 format and that is the reason why it is “converted” to the expected input for this model.

Cheers,

Olivier

On 27 Jun 2015, at 10:51, Juhi Dutta <email address hidden> wrote:

> New question #268605 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/268605
>
> Hi,
>
> I am working in MG5_aMC_v2_2_3. I am trying to compute decays of some particles in mssm.
>
> I generate the process and output file using the model mssm . I replace the param_card.dat file to my desired param_card.dat (generated using susyhit and converted to SLHA2 format).
>
> I change the decay widths of x1+ to auto in the param card (by replacing the decay width value to Auto).Then I go on to use compute_widths x1+ (from bin/madevent)
>
> At the end of the run, my param_card.dat gets replaced by the default param_card.dat with the calculated decay width .This is a bit confusing as it is not making the changes in my current param_card.dat but using a default version.
>
> Is there something I have missed? Kindly advise.
>
> Regards,
>
> Juhi
>
>
>
>
>
> --
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> contact for MadGraph5_aMC@NLO.

Hi,

Sorry for the delayed response .

I repeated the above using the SLHA1 card. This time I only set the decay width of top to AUTO. The run crashed outwith the following error message :

compute_widths 6 --precision_channel=0.01 --body_decay=4.0025 --path=/home/juhi/Juhi_Docs/MG5_aMC_v2_2_3/sphsusy5/Cards/param_card.dat --output=/home/juhi/Juhi_Docs/MG5_aMC_v2_2_3/sphsusy5/Cards/param_card.dat
Be carefull automatic computation of the width is
ONLY valid in Narrow-Width Approximation and at Tree-Level.
Command "generate_events run_01" interrupted in sub-command:
"set complex_mass_scheme False" with error:
MadGraph5Error : decay (23,) not define

Here the top decay width has been set to 1.0 in the param_card.dat after the unsuccessful run.

Any idea how I could trace back to this "set complex mass scheme False" ? Any other suggestions in this regard will be very helpful.

Regards,
Juhi

The problem is that some of the SM particle do not have the width defined in your input card.
This is a flaw which is typical from some SUSY calculator. (they do not include the SM masses typically)

Cheers,

Olivier