local variable 'pols' referenced before assignment

Asked by Shubhani Jain on 2021-01-18


I have been trying to generate events for g g > h2 > h1 h1 with each h1 > b b~ [QCD] using 2HDMII_nlo model (madgraph model 2.7.2). I have also edited run_card.dat to implement pt cuts on h1 otherwise they aren't implemented on b. I used my collaborators run_card as my run_card doesn't show much option for pts, eta and ecut. After running madevent and then madspin I get this error:

Command "generate_events run_01" interrupted with error:
UnboundLocalError : local variable 'pols' referenced before assignment
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in '/scratch/sj1n19/MG5/MG5_aMC_v2_7_2/check/run_01_tag_1_debug.log'.
Please attach this file to your report.

I also attach my debug log:

I am also attaching the run_card.dat that I get before edit it .


Question information

English Edit question
MadGraph5_aMC@NLO Edit question
No assignee Edit question
Solved by:
Olivier Mattelaer
Last query:
Last reply:

This question was reopened

This sounds a MadSpin issue.
can you also attach your madspin card?


Shubhani Jain (s2697661) said : #2

Hi Olivier

Thanks for the reply.

I have updated the dropbox with madspin card.



OK, your madspin card is actually not valid for what you want to do
you just have to have
decay h1 > b b~

if you wanted to decay each h1 to something different you would have need the following syntax:
decay h1 > b b~
decay h1 > a a

syntax like this one are valid
decay t > w+ b, w+ > all all
but this is intended for a chain decay

I actually do not know if this is your exact issue but it is likely that if you use the correct syntax it will go trough and will work.


Shubhani Jain (s2697661) said : #4

Hi Olivier

I have to decay both h1 to b b~ (as g g > h2 > h1 h1). So what syntax should be valid for this ?


Shubhani Jain (s2697661) said : #5

 For more info we are generating g g > h2 in madgraph, then decaying to the two h1's and subsequently each h1 to bb~ pairs in MadSpin

Shubhani Jain (s2697661) said : #6

So would decay h1 > b b~ works for both h1?

Your syntax is
g g > h2 > h1 h1 [QCD]
This means do generate two h1 in the final state from two gluon in the initial state and you need to have at least one h2 in S-channel somewhere (this is the > h2 >). Note the logic, since while for your process this is the same as what you said it is not the same in general.

The syntax that you are looking for in the madspin_card.dat is simply
set spinmode=none
decay h1 > b b~



Shubhani Jain (s2697661) said : #8

Okay, thanks. I will try this.

Shubhani Jain (s2697661) said : #9

Thanks Olivier Mattelaer, that solved my question.