MadGraph5_aMC@NLO

ValueError: not enough values to unpack (expected 2, got 1)

Asked by Si Wang

Hi,

I was running the LQDM model for mu- c > lq process.
The I ran the script:
launch mu-c_lq
analysis=OFF
set mass 42 1000
set nevents 10000
set ebeam1 5000
set ebeam2 5000
set lpp1 0
set lpp2 -1
set pdlabel1 none
set pdlabel2 lhapdf
set lhaid 89999999
set LQLAML 1 1 0.0
set LQLAML 1 2 0.0
set LQLAML 1 3 0.0
set LQLAML 2 1 0.0
set LQLAML 2 2 0.1
set LQLAML 2 3 0.0
set LQLAML 3 1 0.0
set LQLAML 3 2 0.0
set LQLAML 3 3 0.0
set LQLAMR 1 1 0.0
set LQLAMR 1 2 0.0
set LQLAMR 1 3 0.0
set LQLAMR 2 1 0.0
set LQLAMR 2 2 0.1
set LQLAMR 2 3 0.0
set LQLAMR 3 1 0.0
set LQLAMR 3 2 0.0
set LQLAMR 3 3 0.0
set fixed_fac_scale False
set fixed_ren_scale False
set dynamical_scale_choice 4
set no_parton_cut
set use_syst False
0
exit

But it shows the error:
Command "generate_events run_01" interrupted with error:
ValueError : not enough values to unpack (expected 2, got 1)

The error details is:
  File "/home/si/Dropbox/Linux/HEPSoftware/MG5_aMC_v3.5.0/madgraph/madevent/combine_runs.py", line 137, in get_fortran_str
    nb, power = data.split('E')
ValueError: not enough values to unpack (expected 2, got 1)

I guess the error may be data split only return one value, but don't know the reason.

Thanks!
Si

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Solved by:
Olivier Mattelaer
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Revision history for this message
Si Wang (siw34) said (last edit ): 		#1

But the process p p > lq lq~ works fine.
With two p come from muon PDF.

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#2

Hi,

One reason why such error did happened in the past is when some contribution to the cross-section are so small that they are smaller than 1e-100, and then the fortran code fails to write correctly the associated cross-section and therefore the python code that combine them does not have the expected formatting.

Now, I have tried your first process:
but the code crash on my side with
"generate mu- c > lq" with error:
NoDiagramException : No amplitudes generated from process Process: mu- c > lq WEIGHTED=2 @1. Please enter a valid process

So I guess that either i do not use the same model as you, or that I did not understand the first process that you were refering too.

Cheers,

Olivier

Revision history for this message
Si Wang (siw34) said : 		#3

This is full output, maybe helpful:
INFO: End survey
refine 10000
Creating Jobs
INFO: Refine results to 10000
INFO: Generating 10000.0 unweighted events.
sum of cpu time of last step: 0 second
INFO: Effective Luminosity 0.33578643982427175 pb^-1
INFO: need to improve 1 channels
- Current estimate of cross-section: 35737.0 +- 2768.0
    P1_mumc_lq
INFO: Idle: 1, Running: 11, Completed: 0 [ current time: 15h00 ]
INFO: Idle: 0, Running: 11, Completed: 1 [ 4.4s ]
INFO: Idle: 0, Running: 1, Completed: 11 [ 7.8s ]
INFO: Idle: 0, Running: 0, Completed: 12 [ 10.3s ]
INFO: Combining runs
Command "generate_events run_01" interrupted with error:
ValueError : not enough values to unpack (expected 2, got 1)

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#4

Clearly the model that I found online (here: https://phystev.cnrs.fr/wiki/2019:groups:bsm:rdm) does not make any sense since the lq particles does exists but ... does not interact with any other particles...
So I really need that you put the model somewhere if you want me to take a look at this.

Cheers,

Olivier

Revision history for this message
Si Wang (siw34) said : 		#5

This is the model file:
https://feynrules.irmp.ucl.ac.be/wiki/LQDM#no1

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#6

Hi,

Your PDF is not within lhapdf library, so I can not reproduce your run.
If I try with a normal pdf, I do have an issue with the run but something quite different (so maybe not related).
My error is (within 3.5.3):

INFO: Idle: 1, Running: 0, Completed: 0 [ current time: 04h57 ]
At line 1756 of file dsample.f
Fortran runtime error: Index '0' of dimension 2 of array 'grid' below lower bound of 1

Which seems related to the assymetric beam setup (that I will investigate next week).

Cheers,

Olivier

Revision history for this message
Best Olivier Mattelaer (olivier-mattelaer) said : 		#7

Hi,

The problem is related to the fact that the question does not make that sense.
For this 2>1 process, the dimension of the phase-space is problematic. Indeed the dimension is
3 (number of degrees of freedom for the final state) -4 (conservation of energy-momentum) + 1 (PDF on one beam)
So this is exactly zero.

In other word, they are no need to do a phase-space integral since only one kinematical momenta will have the requested kinematic. The problem is so simple that you would need to do the convolution by hand since the generation of events need to have at least one dimension to integrate on.

One solution is to add the decay of your lepto-quark and/or to add some ISR/...

Cheers,

Olivier

Revision history for this message
Si Wang (siw34) said : 		#8

Thanks, Olivier! That explains everything.
Cheers,
Si