ttbar production [QCD]

[Francesco Giuli]

Hi everybody,
I'm using MG5_aMC_v2_2_1and I’m trying to validate the FxFx merging in aMC@NLO, studying the tt~ + jets production.
I’ve generated my event sample in the following way:
- import model sm-no_bmass
- generate p p > t t~ [QCD] @0
- add process p p > t t~ j [QCD] @1
- add process p p > t t~ j j [QCD] @2
- import model loop_sm-no_bmass
- output ttbar_QCD
- launch (I’ve already studied the W + jets process, so I’ve set, in both the run_card.dat and in the shower_card.dat, the ‘correct values’ for FxFx merging flags (e.g. ickkw = 3) and I’ve changed the default set of PDF —> I’m working with lhapdf 260000 [NNPDF-3.0].
After compiling the P* directories, the program stopped, getting this error:

/afs/cern.ch/work/f/fgiuli/public/MG5_aMC_v2_2_1/ttbar_QCD/SubProcesses/P2_gux_ttxuxg/ajob3: line 24: 6521 Segmentation fault (core dumped) ../madevent_mintMC > log.txt < input_app.txt 2>&1

WARNING: program /afs/cern.ch/work/f/fgiuli/public/MG5_aMC_v2_2_1/ttbar_QCD/SubProcesses/P2_gux_ttxuxg/ajob3 2 F 0 launch ends with non zero status: 139. Stop all computation

WARNING: Last 15 lines of logfile
/afs/cern.ch/work/f/fgiuli/public/MG5_aMC_v2_2_1/ttbar_QCD/SubProcesses/P2_gux_ttxuxg/*/log.txt:

 INFO: MadLoop read these parameters from ../MadLoop5_resources/MadLoopParams.dat

INFO: remove job currently running
/afs/cern.ch/work/f/fgiuli/public/MG5_aMC_v2_2_1/ttbar_QCD/SubProcesses/P2_gux_ttxuxg/ajob1: line 24: 6441 Terminated ../madevent_mintMC > log.txt < input_app.txt 2>&1
INFO: remove job currently running

Has anyone ever seen an error like that?

Thanks,
Francesco

[Rikkert Frederix (frederix)]

Dear Francesco,

I cannot reproduce your problem. Could you go to the

/afs/cern.ch/work/f/fgiuli/public/MG5_aMC_v2_2_1/ttbar_QCD/SubProcesses/P2_gux_ttxuxg/GF3

directory and execute

../madevent_mintMC <input_app.txt

by hand and let me know if there is the same error?

Best regards,
Rikkert

P.S. If you use a model without a b quark mass, you should include the b quark in the definition of the 'p' and the 'j'. Did you do that?

[Francesco Giuli (francesco-giuli)]

Hi,
I cannot find the directory you linked previously.
As regards the model without a b quark mass, I included the b quark in proton and jet definitions, as follows:
- import model sm-no_bmass
- define p = p b b~
- define j = p
- import model loop_sm-no_bmass

Cheers,
Francesco

[Rikkert Frederix (frederix)]

Do you have any G* directories in the process folders related to the ttbar+2j matrix elements, i.e. SubProcesses/P2_*/G* directories?

Best,
Rikkert

[Francesco Giuli (francesco-giuli)]

Hi Rikkert,
I don't know why now, if I try to launch the directory with p p > t t~ + 2j [NLO], a compilation Error occurs when trying to compile P2_gg_ttxuux directory! :(
Anyway... As suggested in your article (arXiv:1209.6215.v1 - Merging meets matching in MC@NLO), I limited top-anti top production to the case t t~ + 1j [NLO]. After compiling all the P* directories and after

INFO: Starting run
INFO: Using 8 cores
INFO: Cleaning previous results
INFO: Doing NLO matched to parton shower
INFO: Setting up grid
INFO: Idle: 42, Running: 8, Completed: 0 [ current time: 03h09 ]
INFO: Idle: 41, Running: 8, Completed: 1 [ 41.5s ]
INFO: Idle: 40, Running: 8, Completed: 2 [ 41.6s ]
INFO: Idle: 39, Running: 8, Completed: 3 [ 45.4s ]
INFO: Idle: 38, Running: 8, Completed: 4 [ 3m 3s ]
INFO: Idle: 37, Running: 8, Completed: 5 [ 3m 4s ]
INFO: Idle: 36, Running: 8, Completed: 6 [ 5m 50s ]
INFO: Idle: 35, Running: 8, Completed: 7 [ 9m 40s ]
INFO: Idle: 34, Running: 8, Completed: 8 [ 10m 45s ]

, I get this error:

/afs/cern.ch/work/f/fgiuli/public/MG5_aMC_v2_2_2/ttbar_j_NLO/SubProcesses/P1_gg_ttxg/GF3: line 24: 12228 Segmentation fault (core dumped) ../madevent_mintMC > log.txt < input_app.txt 2>&1
WARNING: program /afs/cern.ch/work/f/fgiuli/public/MG5_aMC_v2_2_2/ttbar_j_NLO/SubProcesses/P1_gg_ttxg/ajob3 2 F 0 launch ends with non zero status: 139. Stop all computation

Then, as you suggested me previously, I went to /afs/cern.ch/work/f/fgiuli/public/MG5_aMC_v2_2_2/ttbar_j_NLO/SubProcesses/P1_gg_ttxg/ and I execute '../madevent_mintMC <input_app.txt'.
I have obtained:

 ---- POLES CANCELLED ----
../madevent_mintMC <input_app.txt ERROR, NaN found for dsigS, setting dsigS to 0 for this event
 ERROR, NaN found for dsigS, setting dsigS to 0 for this event

and then the program stucked.
What have I to do?

Cheers,
Francesco

[Francesco Giuli (francesco-giuli)]

After like 20 minutes...

ABS integral = Infinity +/- NaN ( NaN %)
Integral = -Infinity +/- NaN ( NaN %)
Virtual = -Infinity +/- NaN ( NaN %)
Virtual ratio = NaN +/- NaN ( NaN %)
ABS virtual = Infinity +/- NaN ( NaN %)
Born*ao2pi = 0.2855E-02 +/- 0.2858E-03 ( 10.012 %)
Chi^2 per d.o.f. 0.0000E+00
accumulated results ABS integral = Infinity +/- NaN ( NaN %)
accumulated results Integral = -Infinity +/- NaN ( NaN %)
accumulated results Virtual = -Infinity +/- NaN ( NaN %)
accumulated results Virtual ratio = NaN +/- NaN ( NaN %)
accumulated results ABS virtual = Infinity +/- NaN ( NaN %)
accumulated results Born*ao2pi = 0.2855E-02 +/- 0.2858E-03 ( 10.012 %)
accumulated result Chi^2 per DoF = 0.0000E+00
update virtual fraction to: 1.000 -Inf
  1: 0 1 2 3 4 5
 ------- iteration 2
 Update # PS points (even): 1600 --> 1600

Program received signal SIGSEGV: Segmentation fault - invalid memory reference.

Backtrace for this error:
#0 0x7F53F592F2F7
#1 0x7F53F592F8FE
#2 0x7F53F438F69F
#3 0x49CB87
#4 0x49E221
#5 0x4A6A24
#6 0x4AA23B
#7 0x7F53F437BD5C
#8 0x413D5C
Segmentation fault (core dumped)

I really don't know waht I have to do.

Francesco

[Rikkert Frederix (frederix)]

Dear Francesco,

Sorry for the complete silence. Could you try updating to 2.2.3 (released today) and let me know if the problem persists?

best regards,
Rikkert

[Onur Karayalcin (karayalcino)]

Dear Rikkert,

I think I have the same problem. I'm using MG5_aMC_v2_5_2 and I’m trying to validate the FxFx merging in aMC@NLO, studying the tt~ + jets production.I’ve generated my event sample inclusively in the following way:
- import model sm
- generate p p > t t~ [QCD] @0
- add process p p > t t~ j [QCD] @1
- add process p p > t t~ j j [QCD] @2
- output PROC_$MODELNAME_$X

../PROCNLO_loop_sm_2/ directory is created after compile with command ./bin/mg5_aMC proc_card.dat
To launch, I used commands

cd PROCNLO_loop_sm_2/
./bin/generate_events

- launch (I’ve set, in both the run_card.dat and in the shower_card.dat, the ‘correct values’ for FxFx merging flags (e.g. ickkw = 3, #ofevents=20000, beam energy=7000TeV for both, qcut=50, PYTHIA8=Shower) and I’ve not changed the default options like PDFsets. After compile, it is written on the terminal screen,

.
.
INFO: Poles successfully cancel for 20 points over 20 (tolerance=1.0e-05)
INFO: Starting run
INFO: Using 4 cores
INFO: Cleaning previous results
INFO: Doing NLO matched to parton shower
INFO: Setting up grids
INFO: Idle: 405, Running: 4, Completed: 0 [ current time: 11h10 ]
INFO: Idle: 404, Running: 4, Completed: 1 [ 3.9s ]
INFO: Idle: 402, Running: 4, Completed: 3 [ 8.4s ]
INFO: Idle: 401, Running: 4, Completed: 4 [ 8.4s ]
INFO: Idle: 400, Running: 4, Completed: 5 [ 8.7s ]
/Users/onurkarayalcin/Programs/aMCNLO-1/MG5_aMC_v2_5_2/PROCNLO_loop_sm_2/SubProcesses/P2_gg_ttxg/ajob1: line 34: 12375 Segmentation fault: 11 ../madevent_mintMC > log.txt < input_app.txt 2>&1
WARNING: program /Users/onurkarayalcin/Programs/aMCNLO-1/MG5_aMC_v2_5_2/PROCNLO_loop_sm_2/SubProcesses/P2_gg_ttxg/ajob1 4 F 0 0 launch ends with non zero status: 139. Stop all computation
INFO: Idle: 400, Running: 3, Completed: 6 [ 18.7s ]
INFO: Idle: 400, Running: 2, Completed: 7 [ 18.8s ]
INFO: Idle: 400, Running: 1, Completed: 8 [ 18.8s ]
INFO: Idle: 400, Running: 0, Completed: 9 [ 18.9s ]
.
.

I get segmentation error(I repeated the procedure for pp>tt~ j process inclusively but it gives the same error) and stop all computation. Then, I describe your recommendations and applied respectively. I go to the

/Users/onurkarayalcin/Programs/aMCNLO-1/MG5_aMC_v2_5_2/PROCNLO_loop_sm_2/SubProcesses/P2_gg_ttxg/GF3

directory and execute

../madevent_mintMC <input_app.txt

command. So, it gives the error like

ERROR :: MadFKS parameter file FKS_params.dat could not be found or is malformed. Please specify it.

And I tried it for other GF* directories and other P2_* directories, however I get the same error. Additionally, I have G* files for all process folders for tt~ +2j process. Secondly, P1* subprocess directories work without any error.

I can not get the source of error exactly. Is it related to PDFsets? Would you help and guide me?

Best,
Onur