loop_sm model- associated production of higgs

Hi,

If I remember correctly such loop are analytically zero due to the furry theorem.
Consequently we do not include them within our computation.

Cheers,

Olivier

> On 27 Dec 2019, at 10:58, Antara Sarkar <email address hidden> wrote:
>
> New question #687574 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/687574
>
> Within model loop_sm, I am trying to higgs and photon with the syntax:
> generate p p > h a [virt=QED]
> I get only diagrams with initial gluons. I expect higgs and photon production from quarks also (involving one loop). For example, with:
> generate p p > h z [virt=QED]
> I get all contributions from fermion loops as well as W loop and other diagrams from incoming particles gluons or be it quarks. Could you please explain why there is no production of higgs and photon from initial quarks?
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

So, do you mean that if I consider a SM process where two quarks collide to produce a higgs and a photon which is a loop induced process with an off shell photon or Z boson produced from the quarks, the amplitude for this process is zero?

Regards,
Tisa

I just mean that the loop induced diagram that are missing are zero.

Cheers,

Olivier

> On 27 Dec 2019, at 15:43, antara sarkar <email address hidden> wrote:
>
> Question #687574 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/687574
>
> antara sarkar requested more information:
> So, do you mean that if consider a SM process where two quarks collide
> to produce a higgs and a photon which is a loop induced process with an
> off shell photon or Z boson produced from the quarks, the amplitude for
> this process is zero?
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

OK,

Looks like you are not complaining about the missing diagram related to Furry theorem here.
But just about the standard selection of diagram which keeps only the first term in the perturbative expansion in QCD/QED.
If you want to include the quark as well you need to use a syntax specifying that you want to include other term in the perturbative expansion:
generate p p > h a QED<=99 [virt=QED]

Hi Olivier,

Got this point. Thanks for the help.

Regards,
Tisa

Thanks Olivier Mattelaer, that solved my question.

Hi,
I still am facing problem in generating the events.
When I give the following commands:
generate p p > h z [virt=QED]
output hzproductn
launch
No events are run and only param_card.dat and MadLoopParams.dat appear. However, g g > h z [virt=QED], the events run fine giving an appropriate cross-section. Could you please how to solve this problem for p p > h z?

Hi,

The syntax [virt=QED] is a syntax that does not allow event generation.
So I do not see how you can get events with such syntax (I do not reproduce your behavior)

If you want to have event generation for loop induced the correct syntax is
generate g g > h z [noborn=QED]
Note that such syntax assumes that you are in a valid loop-induced mode if you are not (i.e. a tree-level diagram exists for such initial/final state) then your result are not physical obviously.

Cheers,

Olivier

Hi,
Thanks. The events are generated for the higgs, Z boson production. But I was also trying for higgs and photon production. As I launch, an error is coming out. Not able to understand the error. Could you please help?
MG5_aMC>generate p p > h a [noborn = QED]
INFO: Checking for minimal orders which gives processes.
INFO: Please specify coupling orders to bypass this step.
INFO: Trying coupling order WEIGHTED<=4: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=5: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=6: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=7: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=8: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=9: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=10: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=11: WEIGTHED IS 2*QED+QCD
INFO: Contributing diagrams generated: 0 Born, 6 loops, 0 R2, 0 UV
INFO: Contributing diagrams generated: 0 Born, 66 loops, 4 R2, 2 UV
INFO: Contributing diagrams generated: 0 Born, 66 loops, 4 R2, 2 UV
INFO: Contributing diagrams generated: 0 Born, 66 loops, 4 R2, 2 UV
INFO: Contributing diagrams generated: 0 Born, 66 loops, 4 R2, 2 UV
INFO: Process u~ u > h a added to mirror process u u~ > h a
INFO: Process c~ c > h a added to mirror process c c~ > h a
INFO: Process d~ d > h a added to mirror process d d~ > h a
INFO: Process s~ s > h a added to mirror process s s~ > h a
INFO: Contributing diagrams generated: 0 Born, 101 loops, 4 R2, 2 UV
INFO: Process b~ b > h a added to mirror process b b~ > h a
6 processes with 371 diagrams generated in 6.451 s
Total: 6 processes with 371 diagrams
MG5_aMC>output haproduction
INFO: directory /home/ad/MG5_aMC_v2_5_5/haproduction already exists.
If you continue this directory will be deleted and replaced.
Do you want to continue? [y, n][60s to answer]
>y
INFO: initialize a new directory: haproduction
INFO: remove old information in haproduction
INFO: Organizing processes into subprocess groups
INFO: Generating Helas calls for process: b b~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Processing color information for loop process: b b~ > h a [ noborn = QED ]
INFO: Creating color matrix loop process: b b~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Generating Helas calls for process: u u~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Processing color information for loop process: u u~ > h a [ noborn = QED ]
INFO: Creating color matrix loop process: u u~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Combined process c c~ > h a WEIGHTED<=60 [ noborn = QED ] with process u u~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Generating Helas calls for process: d d~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Reusing existing color information for loop process: d d~ > h a [ noborn = QED ]
INFO: Reusing existing color matrix for loop process: d d~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Combined process s s~ > h a WEIGHTED<=60 [ noborn = QED ] with process d d~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Generating Helas calls for process: g g > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Processing color information for loop process: g g > h a [ noborn = QED ]
INFO: Creating color matrix loop process: g g > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Creating files in directory /home/ad/MG5_aMC_v2_5_5/haproduction/SubProcesses/PV0_0_1_bbx_ha
ALOHA: aloha creates FFV2 set of routines with options: L1,P0
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b b~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Creating files in directory /home/ad/MG5_aMC_v2_5_5/haproduction/SubProcesses/PV0_0_2_uux_ha
ALOHA: aloha creates FFV5 set of routines with options: L1,P0
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: u u~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Creating files in directory /home/ad/MG5_aMC_v2_5_5/haproduction/SubProcesses/PV0_0_3_ddx_ha
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: d d~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Creating files in directory P0_qq_ha
INFO: Generating Feynman diagrams for Process: b b~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Generating Feynman diagrams for Process: u u~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Generating Feynman diagrams for Process: d d~ > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Finding symmetric diagrams for subprocess group qq_ha
INFO: Creating files in directory /home/ad/MG5_aMC_v2_5_5/haproduction/SubProcesses/PV0_1_1_gg_ha
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: g g > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Creating files in directory P0_gg_ha
INFO: Generating Feynman diagrams for Process: g g > h a WEIGHTED<=60 [ noborn = QED ]
INFO: Finding symmetric diagrams for subprocess group gg_ha
History written to /home/ad/MG5_aMC_v2_5_5/haproduction/Cards/proc_card_mg5.dat
Generated helas calls for 4 subprocesses (239 diagrams) in 0.955 s
ALOHA: aloha creates l_HWpWm20 routines
ALOHA: aloha creates FFV2 set of routines with options: L3
ALOHA: aloha creates FFV1 routines
ALOHA: aloha creates VVS1 routines
The option gauge is modified [unitary] but will not be written in the configuration files.
If you want to make this value the default for future session, you can run 'save options --all'
save configuration file to /home/ad/MG5_aMC_v2_5_5/haproduction/Cards/me5_configuration.txt
INFO: Use Fortran compiler gfortran
INFO: Use c++ compiler g++
INFO: Generate jpeg diagrams
INFO: Generate web pages
Output to directory /home/ad/MG5_aMC_v2_5_5/haproduction done.
Type "launch" to generate events from this process, or see
/home/ad/MG5_aMC_v2_5_5/haproduction/README
Run "open index.html" to see more information about this process.
MG5_aMC>launch
************************************************************
* *
* W E L C O M E to *
* M A D G R A P H 5 _ a M C @ N L O *
* M A D E V E N T *
* *
* * * *
* * * * * *
* * * * * 5 * * * * *
* * * * * *
* * * *
* *
* VERSION 2.5.5 2017-05-26 *
* *
* The MadGraph5_aMC@NLO Development Team - Find us at *
* https://server06.fynu.ucl.ac.be/projects/madgraph *
* *
* Type 'help' for in-line help. *
* *
************************************************************
INFO: load configuration from /home/ad/MG5_aMC_v2_5_5/haproduction/Cards/me5_configuration.txt
INFO: load configuration from /home/ad/MG5_aMC_v2_5_5/input/mg5_configuration.txt
INFO: load configuration from /home/ad/MG5_aMC_v2_5_5/haproduction/Cards/me5_configuration.txt
Using default text editor "vi". Set another one in ./input/mg5_configuration.txt
generate_events run_01
The following switches determine which programs are run:
/--------------------------------------------------------------------------------------------------\
| 1. Choose the shower/hadronization program: shower = OFF |
| 2. Choose the detector simulation program: detector = OFF |
| 3. Run an analysis package on the events generated: analysis = MADANALYSIS_4 |
| 4. Decay particles with the MadSpin module: madspin = OFF |
| 5. Add weights to events for different model hypothesis: reweight = OFF |
\--------------------------------------------------------------------------------------------------/
  Either type the switch number (1 to 5) to change its setting,
  Set any switch explicitly (e.g. type 'madspin=ON' at the prompt)
  Type 'help' for the list of all valid option
  Type '0', 'auto', 'done' or just press enter when you are done.
 [0, auto, done, delphes, delphes=ON, delphes=OFF, shower=OFF, shower=PYTHIA8, shower, detector=OFF, ... ][60s to answer]
>0
Do you want to edit a card (press enter to bypass editing)?
/------------------------------------------------------------\
| 1. param : param_card.dat |
| 2. run : run_card.dat |
| 3. plot : plot_card.dat |
| 4. MadLoopParams : MadLoopParams.dat |
\------------------------------------------------------------/
 you can also
   - enter the path to a valid card or banner.
   - use the 'set' command to modify a parameter directly.
     The set option works only for param_card and run_card.
     Type 'help set' for more information on this command.
   - call an external program (ASperGE/MadWidth/...).
     Type 'help' for the list of available command
 [0, done, 1, param, 2, run, 3, plot, 4, enter path, ... ][90s to answer]
>2
open /home/ad/MG5_aMC_v2_5_5/haproduction/Cards/run_card.dat
Do you want to edit a card (press enter to bypass editing)?
/------------------------------------------------------------\
| 1. param : param_card.dat |
| 2. run : run_card.dat |
| 3. plot : plot_card.dat |
| 4. MadLoopParams : MadLoopParams.dat |
\------------------------------------------------------------/
 you can also
   - enter the path to a valid card or banner.
   - use the 'set' command to modify a parameter directly.
     The set option works only for param_card and run_card.
     Type 'help set' for more information on this command.
   - call an external program (ASperGE/MadWidth/...).
     Type 'help' for the list of available command
 [0, done, 1, param, 2, run, 3, plot, 4, enter path, ... ]
>0
INFO: Update the dependent parameter of the param_card.dat
WARNING: Failed to update dependent parameter. This might create trouble for external program (like MadSpin/shower/...)
Generating 100000 events with run name run_01
survey run_01
INFO: compile directory
initMadLoop -r -f
Initializing MadLoop loop-induced matrix elements (this can take some time)...
MadLoop initialization finished.
compile Source Directory
Using random number seed offset = 21
INFO: Running Survey
Creating Jobs
Working on SubProcesses
INFO: P0_qq_ha
INFO: P0_gg_ha
INFO: Idle: 6, Running: 4, Completed: 0 [ current time: 13h55 ]
INFO: Idle: 5, Running: 4, Completed: 1 [ 0.92s ]
INFO: Idle: 3, Running: 4, Completed: 6 [ 4.4s ]
INFO: P0_qq_ha/G2 is at 4.34e-05 +- 3.02e-06 pb. Now submitting iteration #2.
INFO: P0_qq_ha/G1 is at 4.89e-05 +- 5.45e-06 pb. Now submitting iteration #2.
INFO: P0_qq_ha/G3 is at 5.89e-05 +- 3e-05 pb. Now submitting iteration #2.
INFO: Idle: 4, Running: 4, Completed: 12 [ 10.2s ]
INFO: Idle: 3, Running: 4, Completed: 14 [ 16.5s ]
INFO: P0_qq_ha/G4.2 is at 0.000103 +- 2.5e-05 pb. Now submitting iteration #2.
INFO: Idle: 3, Running: 4, Completed: 17 [ 20.4s ]
INFO: P0_qq_ha/G2 is at 5.38e-05 +- 5.57e-06 pb. Now submitting iteration #3.
INFO: P0_qq_ha/G1 is at 5.28e-05 +- 1.07e-06 pb. Now submitting iteration #3.
INFO: Idle: 4, Running: 4, Completed: 21 [ 24.9s ]
INFO: Idle: 3, Running: 4, Completed: 23 [ 35s ]
INFO: P0_qq_ha/G3 is at 4.49e-05 +- 3.16e-06 pb. Now submitting iteration #3.
INFO: P0_qq_ha/G4.2 is at 7.38e-05 +- 3.77e-06 pb. Now submitting iteration #3.
INFO: Idle: 4, Running: 4, Completed: 27 [ 46.4s ]
INFO: P0_qq_ha/G2 is at 5.71e-05 +- 3.45e-06 pb. Now submitting iteration #4.
INFO: Idle: 4, Running: 4, Completed: 30 [ 54.9s ]
INFO: Idle: 3, Running: 4, Completed: 32 [ 1m 3s ]
INFO: P0_qq_ha/G1 is at 5.08e-05 +- 1.13e-06 pb. Now submitting iteration #4.
INFO: Survey finished for P0_qq_ha/G3 at 4.12e-05 +- 8.02e-07 pb
INFO: P0_qq_ha/G4.2 is at 7.17e-05 +- 1.73e-06 pb. Now submitting iteration #4.
INFO: Idle: 3, Running: 4, Completed: 37 [ 1m 24s ]
INFO: Idle: 2, Running: 4, Completed: 39 [ 1m 47s ]
INFO: P0_qq_ha/G2 is at 5.73e-05 +- 1.62e-06 pb. Now submitting iteration #5.
INFO: Survey finished for P0_qq_ha/G1 at 5.07e-05 +- 5.67e-07 pb
INFO: Idle: 1, Running: 4, Completed: 43 [ 2m 5s ]
INFO: Survey finished for P0_qq_ha/G4.2 at 7.16e-05 +- 7.97e-07 pb
INFO: Idle: 0, Running: 3, Completed: 46 [ 2m 45s ]
INFO: Survey finished for P0_qq_ha/G2 at 5.83e-05 +- 9.85e-07 pb
INFO: Idle: 0, Running: 1, Completed: 49 [ 4m 6s ]
INFO: Idle: 1, Running: 0, Completed: 50 [ 4m 27s ]
CRITICAL: Channel 1 has encountered a fraction of 0.336
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
WARNING: Channel 1 has encountered a fraction of 0.336
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
INFO: Idle: 0, Running: 0, Completed: 51 [ 4m 27s ]
Channel 1 has encountered a fraction of 0.336
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
Cluster Error detected. Do you want to clean the queue? ("c"=continue the run anyway) [y, n, c][60s to answer]
>
use y
Command "generate_events run_01" interrupted with error:
Exception : Channel 1 has encountered a fraction of 0.336
 of numerically unstable loop matrix element computations
 (which could not be rescued using quadruple precision).
 The results can not be trusted.
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in '/home/dell/MG5_aMC_v2_5_5/haproduction/run_01_tag_1_debug.log'.
Please attach this file to your report.
INFO:

INFO:

quit
INFO:

INFO:

The error means that we are not able to evaluate the loop for 33% of the phase-space point of a given channel of integration.
Loop computation can suffer from numerical accuracy issues and this seems to be problematic for this process.

The computation of the loop is technically done via three step/tools
1) the evaluation of the numerator
2) the decomposition of the loop in scalar integral
3) a library returning the result based on the decompostion in the scalar integral.

The issue of numerical accuracy is in the second step.
In our case, we can link to various tools to perform this second step. Each tools used different method (OPP/TIR/...)
and we can dynamically switch from one method to another at run time when we realise that a method does not provide trustable value of the matrix-element.
So the question is which one have you installed?
if you run "install looptools"
you should get a view of the various options that are available:

Which one do you want to install? (this needs to be done only once)
1. cuttools (OPP) [0711.3596] : /Users/omattelaer/Documents/HEPTools
2. iregi (TIR) [1405.0301] : /Users/omattelaer/Documents/HEPTools
3. ninja (OPP) [1403.1229] : /Users/omattelaer/Documents/HEPTools/ninja/lib
4. collier (TIR) [1604.06792] : /Users/omattelaer/Documents/HEPTools/collier
5. golem (TIR) [0807.0605] : do not install
You can:
 -> hit 'enter' to proceed
 -> type a number to cycle its options
 -> enter the following command:
    {tool_name} [install|noinstall|{prefixed_installation_path}]

I see that you are using an old version of the code (2.5.x), it is possible that some powerfull option (i.e. collier) are not available for you. If that's the case, I would strongly suggest to update to the most recent version of the code.

Note that you might want also to check literature to see if this process does not have an integrable singularity in which case, you would need a specific cut to remove that divergency which is likely going to solve your issue.
(typically a 1 Gev cut on the pt of the Higgs/phototn can fix such type of issue)

Cheers,

Olivier

I installed the latest version MG5_aMC_v2_6_7 and and among the looptools, ninja and collier are installed. I put a cut on the pt of photon. However, higgs being a propagator, could you tell how to put a pT cut on it?
And the problem persists.
MG5_aMC>launch
************************************************************
* *
* W E L C O M E to *
* M A D G R A P H 5 _ a M C @ N L O *
* M A D E V E N T *
* *
* * * *
* * * * * *
* * * * * 5 * * * * *
* * * * * *
* * * *
* *
* VERSION 2.6.7 2019-10-16 *
* *
* The MadGraph5_aMC@NLO Development Team - Find us at *
* https://server06.fynu.ucl.ac.be/projects/madgraph *
* *
* Type 'help' for in-line help. *
* *
************************************************************
INFO: load configuration from /home/dell/final/MG5_aMC_v2_6_7/haproduction/Cards/me5_configuration.txt
INFO: load configuration from /home/dell/final/MG5_aMC_v2_6_7/input/mg5_configuration.txt
INFO: load configuration from /home/dell/final/MG5_aMC_v2_6_7/haproduction/Cards/me5_configuration.txt
Using default text editor "vi". Set another one in ./input/mg5_configuration.txt
generate_events run_01
The following switches determine which programs are run:
/=================== Description ===================|============= values ==============|======== other options ========\
| 1. Choose the shower/hadronization program | shower = OFF | Pythia8 |
| 2. Choose the detector simulation program | detector = Not Avail. | Please install module |
| 3. Choose an analysis package (plot/convert) | analysis = Not Avail. | Please install module |
| 4. Decay onshell particles | madspin = OFF | ON|onshell |
| 5. Add weights to events for new hypp. | reweight = OFF | ON |
\=======================================================================================================================/
Either type the switch number (1 to 5) to change its setting,
Set any switch explicitly (e.g. type 'shower=Pythia8' at the prompt)
Type 'help' for the list of all valid option
Type '0', 'auto', 'done' or just press enter when you are done.[60s to answer]
>
Do you want to edit a card (press enter to bypass editing)?
/------------------------------------------------------------\
| 1. param : param_card.dat |
| 2. run : run_card.dat |
| 3. MadLoopParams : MadLoopParams.dat |
\------------------------------------------------------------/
 you can also
   - enter the path to a valid card or banner.
   - use the 'set' command to modify a parameter directly.
     The set option works only for param_card and run_card.
     Type 'help set' for more information on this command.
   - call an external program (ASperGE/MadWidth/...).
     Type 'help' for the list of available command
 [0, done, 1, param, 2, run, 3, MadLoopParams, enter path][90s to answer]
>2
open /home/dell/final/MG5_aMC_v2_6_7/haproduction/Cards/run_card.dat
Do you want to edit a card (press enter to bypass editing)?
/------------------------------------------------------------\
| 1. param : param_card.dat |
| 2. run : run_card.dat |
| 3. MadLoopParams : MadLoopParams.dat |
\------------------------------------------------------------/
 you can also
   - enter the path to a valid card or banner.
   - use the 'set' command to modify a parameter directly.
     The set option works only for param_card and run_card.
     Type 'help set' for more information on this command.
   - call an external program (ASperGE/MadWidth/...).
     Type 'help' for the list of available command
 [0, done, 1, param, 2, run, 3, MadLoopParams, enter path]
>0
INFO: Update the dependent parameter of the param_card.dat
Generating 10000 events with run name run_01
survey run_01
INFO: compile directory
compile Source Directory
Using random number seed offset = 24
INFO: Running Survey
Creating Jobs
Working on SubProcesses
INFO: P0_qq_ah
INFO: P0_gg_ah
INFO: Idle: 6, Running: 4, Completed: 0 [ current time: 18h25 ]
INFO: Idle: 5, Running: 4, Completed: 1 [ 2.1s ]
INFO: Idle: 3, Running: 4, Completed: 5 [ 6s ]
INFO: P0_qq_ah/G2 is at 5.21e-05 +- 3.4e-06 pb. Now submitting iteration #2.
INFO: P0_qq_ah/G1 is at 7.16e-05 +- 1.95e-05 pb. Now submitting iteration #2.
INFO: P0_qq_ah/G3 is at 2.5e-05 +- 2.96e-06 pb. Now submitting iteration #2.
INFO: Idle: 4, Running: 4, Completed: 12 [ 12.6s ]
INFO: Idle: 3, Running: 4, Completed: 14 [ 19.9s ]
INFO: P0_qq_ah/G4.2 is at 5.75e-05 +- 1.87e-05 pb. Now submitting iteration #2.
INFO: P0_qq_ah/G2 is at 6.09e-05 +- 4.8e-06 pb. Now submitting iteration #3.
INFO: P0_qq_ah/G1 is at 5.32e-05 +- 2.94e-06 pb. Now submitting iteration #3.
INFO: Idle: 5, Running: 4, Completed: 19 [ 24.4s ]
INFO: Idle: 4, Running: 4, Completed: 21 [ 29.5s ]
INFO: Idle: 3, Running: 4, Completed: 23 [ 40.6s ]
INFO: P0_qq_ah/G3 is at 3.92e-05 +- 5.79e-06 pb. Now submitting iteration #3.
INFO: Idle: 3, Running: 4, Completed: 26 [ 53.2s ]
INFO: P0_qq_ah/G4.2 is at 5.876e-05 +- 2.33e-07 pb. Now submitting iteration #3.
INFO: P0_qq_ah/G2 is at 6.25e-05 +- 2.18e-06 pb. Now submitting iteration #4.
INFO: Idle: 5, Running: 4, Completed: 29 [ 57s ]
INFO: Idle: 4, Running: 4, Completed: 30 [ 1m 2s ]
INFO: Idle: 4, Running: 4, Completed: 31 [ 1m 6s ]
INFO: Idle: 3, Running: 4, Completed: 32 [ 1m 13s ]
INFO: Idle: 3, Running: 4, Completed: 33 [ 1m 17s ]
INFO: P0_qq_ah/G1 is at 5.54e-05 +- 1.45e-06 pb. Now submitting iteration #4.
INFO: P0_qq_ah/G3 is at 4.17e-05 +- 3.49e-06 pb. Now submitting iteration #4.
INFO: Survey finished for P0_qq_ah/G4.2 at 6.26e-05 +- 9.12e-07 pb
INFO: Idle: 3, Running: 4, Completed: 37 [ 1m 36s ]
INFO: Idle: 3, Running: 4, Completed: 38 [ 1m 40s ]
INFO: Idle: 2, Running: 4, Completed: 39 [ 2m 4s ]
INFO: Survey finished for P0_qq_ah/G2 at 6.33e-05 +- 1.16e-06 pb
INFO: Survey finished for P0_qq_ah/G1 at 5.52e-05 +- 6.81e-07 pb
INFO: Idle: 0, Running: 3, Completed: 43 [ 2m 22s ]
INFO: P0_qq_ah/G3 is at 4.19e-05 +- 1.04e-06 pb. Now submitting iteration #5.
INFO: Idle: 0, Running: 3, Completed: 46 [ 2m 56s ]
INFO: Survey finished for P0_qq_ah/G3 at 4.17e-05 +- 5.06e-07 pb
INFO: Idle: 0, Running: 1, Completed: 49 [ 5m 23s ]
INFO: Idle: 1, Running: 0, Completed: 50 [ 6m 38s ]
CRITICAL: Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
WARNING: Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
INFO: Idle: 0, Running: 0, Completed: 51 [ 6m 38s ]
Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
Cluster Error detected. Do you want to clean the queue? ("c"=continue the run anyway) [y, n, c][60s to answer]
>c
INFO: Idle: 0, Running: 0, Completed: 51 [ current time: 18h32 ]
INFO: Idle: 0, Running: 0, Completed: 51 [ current time: 18h32 ]
Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
Cluster Error detected. Do you want to clean the queue? ("c"=continue the run anyway) [y, n, c][60s to answer]
>c
INFO: Idle: 0, Running: 0, Completed: 51 [ current time: 18h32 ]
Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
Cluster Error detected. Do you want to clean the queue? ("c"=continue the run anyway) [y, n, c][60s to answer]
>
use y
Command "generate_events run_01" interrupted with error:
Exception : Channel 1 has encountered a fraction of 0.492
 of numerically unstable loop matrix element computations
 (which could not be rescued using quadruple precision).
 The results can not be trusted.
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in '/home/dell/final/MG5_aMC_v2_6_7/haproduction/run_01_tag_1_debug.log'.
Please attach this file to your report.
INFO:
quit
INFO:

Why do you say that higgs is a propagator? I do not have your process definition for your last run, but it seems to be in the final states.
In any case, since your have a cut on the photon and since you have a 2to2 process, any cut on the photon will also impact the Higgs.

I will assign our loop-expert to this topic, to see if he has an idea for this particular case.

Cheers,

Olivier

Oops, sorry for that! Yes, I put a cut of 1GeV pT on photon.
I gave the following commands:
import model loop_sm
generate p p > a h [noborn=QED]
output ahproduction
launch

Madgraph is returning this:
************************************************************
* *
* W E L C O M E to *
* M A D G R A P H 5 _ a M C @ N L O *
* M A D E V E N T *
* *
* * * *
* * * * * *
* * * * * 5 * * * * *
* * * * * *
* * * *
* *
* VERSION 2.6.7 2019-10-16 *
* *
* The MadGraph5_aMC@NLO Development Team - Find us at *
* https://server06.fynu.ucl.ac.be/projects/madgraph *
* *
* Type 'help' for in-line help. *
* *
************************************************************
INFO: load configuration from /home/dell/final/MG5_aMC_v2_6_7/haproduction/Cards/me5_configuration.txt
INFO: load configuration from /home/dell/final/MG5_aMC_v2_6_7/input/mg5_configuration.txt
INFO: load configuration from /home/dell/final/MG5_aMC_v2_6_7/haproduction/Cards/me5_configuration.txt
Using default text editor "vi". Set another one in ./input/mg5_configuration.txt
generate_events run_01
The following switches determine which programs are run:
/=================== Description ===================|============= values ==============|======== other options ========\
| 1. Choose the shower/hadronization program | shower = OFF | Pythia8 |
| 2. Choose the detector simulation program | detector = Not Avail. | Please install module |
| 3. Choose an analysis package (plot/convert) | analysis = Not Avail. | Please install module |
| 4. Decay onshell particles | madspin = OFF | ON|onshell |
| 5. Add weights to events for new hypp. | reweight = OFF | ON |
\=======================================================================================================================/
Either type the switch number (1 to 5) to change its setting,
Set any switch explicitly (e.g. type 'shower=Pythia8' at the prompt)
Type 'help' for the list of all valid option
Type '0', 'auto', 'done' or just press enter when you are done.[60s to answer]
>
Do you want to edit a card (press enter to bypass editing)?
/------------------------------------------------------------\
| 1. param : param_card.dat |
| 2. run : run_card.dat |
| 3. MadLoopParams : MadLoopParams.dat |
\------------------------------------------------------------/
 you can also
   - enter the path to a valid card or banner.
   - use the 'set' command to modify a parameter directly.
     The set option works only for param_card and run_card.
     Type 'help set' for more information on this command.
   - call an external program (ASperGE/MadWidth/...).
     Type 'help' for the list of available command
 [0, done, 1, param, 2, run, 3, MadLoopParams, enter path][90s to answer]
>2
open /home/dell/final/MG5_aMC_v2_6_7/haproduction/Cards/run_card.dat
Do you want to edit a card (press enter to bypass editing)?
/------------------------------------------------------------\
| 1. param : param_card.dat |
| 2. run : run_card.dat |
| 3. MadLoopParams : MadLoopParams.dat |
\------------------------------------------------------------/
 you can also
   - enter the path to a valid card or banner.
   - use the 'set' command to modify a parameter directly.
     The set option works only for param_card and run_card.
     Type 'help set' for more information on this command.
   - call an external program (ASperGE/MadWidth/...).
     Type 'help' for the list of available command
 [0, done, 1, param, 2, run, 3, MadLoopParams, enter path]
>0
INFO: Update the dependent parameter of the param_card.dat
Generating 10000 events with run name run_01
survey run_01
INFO: compile directory
compile Source Directory
Using random number seed offset = 24
INFO: Running Survey
Creating Jobs
Working on SubProcesses
INFO: P0_qq_ah
INFO: P0_gg_ah
INFO: Idle: 6, Running: 4, Completed: 0 [ current time: 18h25 ]
INFO: Idle: 5, Running: 4, Completed: 1 [ 2.1s ]
INFO: Idle: 3, Running: 4, Completed: 5 [ 6s ]
INFO: P0_qq_ah/G2 is at 5.21e-05 +- 3.4e-06 pb. Now submitting iteration #2.
INFO: P0_qq_ah/G1 is at 7.16e-05 +- 1.95e-05 pb. Now submitting iteration #2.
INFO: P0_qq_ah/G3 is at 2.5e-05 +- 2.96e-06 pb. Now submitting iteration #2.
INFO: Idle: 4, Running: 4, Completed: 12 [ 12.6s ]
INFO: Idle: 3, Running: 4, Completed: 14 [ 19.9s ]
INFO: P0_qq_ah/G4.2 is at 5.75e-05 +- 1.87e-05 pb. Now submitting iteration #2.
INFO: P0_qq_ah/G2 is at 6.09e-05 +- 4.8e-06 pb. Now submitting iteration #3.
INFO: P0_qq_ah/G1 is at 5.32e-05 +- 2.94e-06 pb. Now submitting iteration #3.
INFO: Idle: 5, Running: 4, Completed: 19 [ 24.4s ]
INFO: Idle: 4, Running: 4, Completed: 21 [ 29.5s ]
INFO: Idle: 3, Running: 4, Completed: 23 [ 40.6s ]
INFO: P0_qq_ah/G3 is at 3.92e-05 +- 5.79e-06 pb. Now submitting iteration #3.
INFO: Idle: 3, Running: 4, Completed: 26 [ 53.2s ]
INFO: P0_qq_ah/G4.2 is at 5.876e-05 +- 2.33e-07 pb. Now submitting iteration #3.
INFO: P0_qq_ah/G2 is at 6.25e-05 +- 2.18e-06 pb. Now submitting iteration #4.
INFO: Idle: 5, Running: 4, Completed: 29 [ 57s ]
INFO: Idle: 4, Running: 4, Completed: 30 [ 1m 2s ]
INFO: Idle: 4, Running: 4, Completed: 31 [ 1m 6s ]
INFO: Idle: 3, Running: 4, Completed: 32 [ 1m 13s ]
INFO: Idle: 3, Running: 4, Completed: 33 [ 1m 17s ]
INFO: P0_qq_ah/G1 is at 5.54e-05 +- 1.45e-06 pb. Now submitting iteration #4.
INFO: P0_qq_ah/G3 is at 4.17e-05 +- 3.49e-06 pb. Now submitting iteration #4.
INFO: Survey finished for P0_qq_ah/G4.2 at 6.26e-05 +- 9.12e-07 pb
INFO: Idle: 3, Running: 4, Completed: 37 [ 1m 36s ]
INFO: Idle: 3, Running: 4, Completed: 38 [ 1m 40s ]
INFO: Idle: 2, Running: 4, Completed: 39 [ 2m 4s ]
INFO: Survey finished for P0_qq_ah/G2 at 6.33e-05 +- 1.16e-06 pb
INFO: Survey finished for P0_qq_ah/G1 at 5.52e-05 +- 6.81e-07 pb
INFO: Idle: 0, Running: 3, Completed: 43 [ 2m 22s ]
INFO: P0_qq_ah/G3 is at 4.19e-05 +- 1.04e-06 pb. Now submitting iteration #5.
INFO: Idle: 0, Running: 3, Completed: 46 [ 2m 56s ]
INFO: Survey finished for P0_qq_ah/G3 at 4.17e-05 +- 5.06e-07 pb
INFO: Idle: 0, Running: 1, Completed: 49 [ 5m 23s ]
INFO: Idle: 1, Running: 0, Completed: 50 [ 6m 38s ]
CRITICAL: Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
WARNING: Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
INFO: Idle: 0, Running: 0, Completed: 51 [ 6m 38s ]
Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
Cluster Error detected. Do you want to clean the queue? ("c"=continue the run anyway) [y, n, c][60s to answer]
>c
INFO: Idle: 0, Running: 0, Completed: 51 [ current time: 18h32 ]
INFO: Idle: 0, Running: 0, Completed: 51 [ current time: 18h32 ]
Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
Cluster Error detected. Do you want to clean the queue? ("c"=continue the run anyway) [y, n, c][60s to answer]
>c
INFO: Idle: 0, Running: 0, Completed: 51 [ current time: 18h32 ]
Channel 1 has encountered a fraction of 0.492
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
Cluster Error detected. Do you want to clean the queue? ("c"=continue the run anyway) [y, n, c][60s to answer]
>
use y
Command "generate_events run_01" interrupted with error:
Exception : Channel 1 has encountered a fraction of 0.492
 of numerically unstable loop matrix element computations
 (which could not be rescued using quadruple precision).
 The results can not be trusted.
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in '/home/dell/final/MG5_aMC_v2_6_7/haproduction/run_01_tag_1_debug.log'.
Please attach this file to your report.
INFO:
quit
INFO:

Dear experts,
I wanted to mention that specifically the problem actually lies in running:
 g g > a h [noborn=QED]
For the quarks, the events for h a production are running all fine.
when I launch this event from gluon initial states, this appears:
MG5_aMC>import model loop_sm
INFO: Restrict model loop_sm with file models/loop_sm/restrict_default.dat .
INFO: Run "set stdout_level DEBUG" before import for more information.
INFO: Change particles name to pass to MG5 convention
Kept definitions of multiparticles l- / j / vl / l+ / p / vl~ unchanged
Defined multiparticle all = g gh gh~ d u s c d~ u~ s~ c~ a ve vm vt e- mu- ve~ vm~ vt~ e+ mu+ b t b~ t~ z w+ h w- ta- ta+
MG5_aMC>generate g g > a h [noborn=QED]
The current model loop_sm does not allow to generate loop corrections of type ['QED'].
Switch to Feynman gauge because model loop_qcd_qed_sm is restricted only to Feynman gauge.
Passing to gauge Feynman.
MG5_aMC now loads 'loop_qcd_qed_sm'.
 import model loop_qcd_qed_sm
INFO: Restrict model loop_qcd_qed_sm with file models/loop_qcd_qed_sm/restrict_default.dat .
INFO: Run "set stdout_level DEBUG" before import for more information.
INFO: Change particles name to pass to MG5 convention
Pass the definition of 'j' and 'p' to 5 flavour scheme.
Kept definitions of multiparticles l- / vl / l+ / vl~ unchanged
Removed obsolete multiparticles all
Defined multiparticle all = g ghg ghg~ u c d s b u~ c~ d~ s~ b~ a gha gha~ ve vm vt e- mu- ta- ve~ vm~ vt~ e+ mu+ ta+ t t~ z w+ ghz ghwp ghwm h g0 g+ w- ghz~ ghwp~ ghwm~ g-
INFO: Checking for minimal orders which gives processes.
INFO: Please specify coupling orders to bypass this step.
INFO: Trying coupling order WEIGHTED<=4: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=5: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=6: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=7: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=8: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=9: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=10: WEIGTHED IS 2*QED+QCD
INFO: Trying coupling order WEIGHTED<=11: WEIGTHED IS 2*QED+QCD
INFO: Contributing diagrams generated: 0 Born, 6 loops, 0 R2, 0 UV
1 processes with 6 diagrams generated in 0.302 s
Total: 1 processes with 6 diagrams
MG5_aMC>output gg2ahproduction
INFO: initialize a new directory: gg2ahproduction
INFO: remove old information in gg2ahproduction
INFO: Organizing processes into subprocess groups
INFO: Generating Helas calls for process: g g > a h WEIGHTED<=12 [ noborn = QED ]
INFO: Processing color information for loop process: g g > a h [ noborn = QED ]
INFO: Creating color matrix loop process: g g > a h WEIGHTED<=12 [ noborn = QED ]
INFO: Creating files in directory /home/dell/my_computation/MG5_aMC_v2_6_7/gg2ahproduction/SubProcesses/PV0_0_1_gg_ah
ALOHA: aloha creates FFV1 set of routines with options: L1
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: g g > a h WEIGHTED<=12 [ noborn = QED ]
INFO: Creating files in directory P0_gg_ah
INFO: Generating Feynman diagrams for Process: g g > a h WEIGHTED<=12 [ noborn = QED ]
INFO: Finding symmetric diagrams for subprocess group gg_ah
Generated helas calls for 1 subprocesses (6 diagrams) in 0.037 s
The option gauge is modified [unitary] but will not be written in the configuration files.
If you want to make this value the default for future session, you can run 'save options --all'
save configuration file to /home/dell/my_computation/MG5_aMC_v2_6_7/gg2ahproduction/Cards/me5_configuration.txt
INFO: Use Fortran compiler gfortran
INFO: Use c++ compiler g++
INFO: Generate jpeg diagrams
INFO: Generate web pages
Output to directory /home/dell/my_computation/MG5_aMC_v2_6_7/gg2ahproduction done.
Type "launch" to generate events from this process, or see
/home/dell/my_computation/MG5_aMC_v2_6_7/gg2ahproduction/README
Run "open index.html" to see more information about this process.
MG5_aMC>launch
************************************************************
* *
* W E L C O M E to *
* M A D G R A P H 5 _ a M C @ N L O *
* M A D E V E N T *
* *
* * * *
* * * * * *
* * * * * 5 * * * * *
* * * * * *
* * * *
* *
* VERSION 2.6.7 2019-10-16 *
* *
* The MadGraph5_aMC@NLO Development Team - Find us at *
* https://server06.fynu.ucl.ac.be/projects/madgraph *
* *
* Type 'help' for in-line help. *
* *
************************************************************
INFO: load configuration from /home/dell/my_computation/MG5_aMC_v2_6_7/gg2ahproduction/Cards/me5_configuration.txt
INFO: load configuration from /home/dell/my_computation/MG5_aMC_v2_6_7/input/mg5_configuration.txt
INFO: load configuration from /home/dell/my_computation/MG5_aMC_v2_6_7/gg2ahproduction/Cards/me5_configuration.txt
Using default text editor "vi". Set another one in ./input/mg5_configuration.txt
generate_events run_01
The following switches determine which programs are run:
/==============================================================================\
| 1. Choose the shower/hadronization program shower = OFF |
| 2. Choose the detector simulation program detector = OFF |
| 3. Choose an analysis package (plot/convert) analysis = MadAnalysis4 |
| 4. Decay onshell particles madspin = OFF |
| 5. Add weights to events for new hypp. reweight = OFF |
\==============================================================================/
Either type the switch number (1 to 5) to change its setting,
Set any switch explicitly (e.g. type 'shower=Pythia8' at the prompt)
Type 'help' for the list of all valid option
Type '0', 'auto', 'done' or just press enter when you are done.[60s to answer]
>0
Do you want to edit a card (press enter to bypass editing)?
/------------------------------------------------------------\
| 1. param : param_card.dat |
| 2. run : run_card.dat |
| 3. plot : plot_card.dat |
| 4. MadLoopParams : MadLoopParams.dat |
\------------------------------------------------------------/
 you can also
   - enter the path to a valid card or banner.
   - use the 'set' command to modify a parameter directly.
     The set option works only for param_card and run_card.
     Type 'help set' for more information on this command.
   - call an external program (ASperGE/MadWidth/...).
     Type 'help' for the list of available command
 [0, done, 1, param, 2, run, 3, plot, 4, enter path, ... ][90s to answer]
>0
INFO: Update the dependent parameter of the param_card.dat
Generating 10000 events with run name run_01
survey run_01
INFO: compile directory
initMadLoop -r -f
Initializing MadLoop loop-induced matrix elements (this can take some time)...
MadLoop initialization finished.
compile Source Directory
Using random number seed offset = 21
INFO: Running Survey
Creating Jobs
Working on SubProcesses
INFO: P0_gg_ah
INFO: Idle: 1, Running: 1, Completed: 0 [ current time: 17h35 ]
INFO: Idle: 0, Running: 1, Completed: 1 [ 4m 43s ]
INFO: Idle: 1, Running: 0, Completed: 2 [ 5m 58s ]
CRITICAL: Channel 1 has encountered a fraction of 0.458
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
WARNING: Channel 1 has encountered a fraction of 0.458
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
INFO: Idle: 0, Running: 0, Completed: 3 [ 5m 58s ]
Channel 1 has encountered a fraction of 0.458
of numerically unstable loop matrix element computations
(which could not be rescued using quadruple precision).
The results can not be trusted.
Cluster Error detected. Do you want to clean the queue? ("c"=continue the run anyway) [y, n, c][60s to answer]
>
use y
Command "generate_events run_01" interrupted with error:
Exception : Channel 1 has encountered a fraction of 0.458
 of numerically unstable loop matrix element computations
 (which could not be rescued using quadruple precision).
 The results can not be trusted.
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in '/home/dell/my_computation/MG5_aMC_v2_6_7/gg2ahproduction/run_01_tag_1_debug.log'.
Please attach this file to your report.
INFO:
quit
INFO:

Could you please help in how to resolve this issue?