MadSpin not finding particle decays

I understand that using madspin is not a wise choice here but what I want is both cross sections from
a. generate p p > mu+ nm, nm > zd vm
b. generate p p > mu+ nm, nm > zd vm, zd > e+ e-
(since zd is very small in mass, BR of zd has to be computed separately) to normalize it properly.

Sorry did not fully write my sentence after this.
I was a bit lazy and wanted to save some computing time by interfacing with MadSpin since doing a.+madspin will give you two separate cross sections, before and after decay.

It seems like there might be an issue with the way you're using MadSpin for the decay process. Here are a few suggestions to address the error:

Check Decay Definitions:
Ensure that the decay definitions in your MadSpin card match the decay channels provided by MadGraph for the process involving zd. The error suggests that MadSpin is not finding a decay definition for the process.

Update MadGraph and MadSpin:
Make sure you are using the latest versions of both MadGraph and MadSpin. Sometimes, bugs are fixed in newer releases, and updating the software may resolve the issue.

Review MadSpin Card:
Double-check the syntax and parameters in your MadSpin card. Ensure that the decay process is correctly specified, and the channels match the ones computed through MadGraph.

Separate BR Calculation:
Since you want to compute the branching ratio (BR) separately for zd, you might consider separating the generation and decay processes. First, generate events with "generate p p > mu+ nm, nm > zd vm," and then compute the BR separately for "generate p p > mu+ nm, nm > zd vm, zd > e+ e-" without using MadSpin.

Check Debug Log:
Review the debug log file ('/home/shjeon/Physics/MCEG/MadGraph/MG5_aMC_v2_9_18/PROC_DarkNeutrino_1/run_01_tag_1_debug.log') for more detailed information on the error. It might provide insights into what specifically went wrong.

Bug Report:
If the issue persists, consider reporting the bug on the MadGraph launchpad (https://gasolineracercaubicaion.com/) with the relevant log files attached. The developers may be able to provide more targeted assistance.

Wow a GPT answer generator lmao

To troubleshoot and resolve this issue, you can try the following steps:

Define the Decay in MadSpin:
Make sure that you have properly defined the decay of the zd particle in your MadSpin configuration. The error suggests that there might be an issue with the decay channels. Check the syntax and correctness of your decay definition.

In your case, it seems like you want to decay zd into e+ e-. Ensure that the decay channel is correctly specified in your MadSpin configuration.

Check MadGraph and MadSpin Compatibility:
Ensure that the version of MadGraph and MadSpin you are using is compatible. Sometimes, certain versions of MadGraph and MadSpin may have compatibility issues. Make sure that you are using versions that are known to work well together.

Review the MadSpin Output:
Examine the MadSpin output for any warnings or errors related to the zd decay. The debug.log file mentioned in the error message ('/home/shjeon/Physics/MCEG/MadGraph/MG5_aMC_v2_9_18/PROC_DarkNeutrino_1/run_01_tag_1_debug.log') may contain useful information about what went wrong.

Update or Modify the Model Files:
Ensure that the model files you are using (DarkNeutrino in this case) are compatible with the decay processes you want to simulate. If necessary, you may need to update or modify the model files to include the desired decay channels.

Consult Documentation and Forums:
Refer to the documentation of MadGraph and MadSpin for the specific version you are using. Additionally, check online forums or community discussions related to MadGraph and MadSpin to see if others have encountered similar issues and have provided solutions or workarounds.

If the issue persists, you may consider reporting the bug to the MadGraph development team or seeking help on their forums or community channels for more specific assistance based on your setup and the versions you are using.

launchpad is polluted :(

Hi,

The reason is that you are mixing decay-chain syntax and madspin and this is not fully supported.
The solution is to let both decay to be handle by madspin like:

import model DarkNeutrino
generate p p > mu+ nm
output mgevents
launch
MadSpin=ON
decay nm > zd vm, zd > e+ e-
#set pdlabel lhapdf
#set lhaid 263400
set no_parton_cut
set eps 0.0001655
set ptl 0.1
set gd 0.25
set thn1 0.0
set thn2 0.31622776601
set thn3 0.0
set mzd 0.030000000000000013
set mne 1.e+10
set mnm 0.09000000000000004
set mnt 1.e+10
set wnm Auto
set run_card lpp1 1
set run_card lpp2 1
set run_card ebeam1 6500.0
set run_card ebeam2 6500.0
set run_card iseed 101
set run_card nevents 10000
set run_card run_tag tag_1
set run_card use_syst False

Cheers,

Olivier

ha i was not aware of this thanks!