Suspicious zero x-section SMEFTsim model
Dear MadGraph experts,
I write to report an unexpected behaviour.
To give you a little bit of background, i am studying the effect of dimension 6 EFT operators to vector boson scattering (VBS) processes. In order to simulate all the Wilson coefficient-
All the simulations went fine for the "one operator case" for the processes of same sign WW production, opposite sign WW EWK, inclusive WW and opposite sign WW QCD production.
Regarding the generation of the interference terms between two operators, MadGraph is not able to compute the amplitudes for all the combinations involving the operator named cHDD for the opposite sign WW QCD production [1]. Restriction cards are created putting every non-interesting operator to exactly 0 while leaving the two interesting ones at 9.999999e-01 [2].
To summarise some important point and to point out why this is suspicious:
1) Mg5 computes non zero amplitudes for the interference term between the SM and the cHDD for all the VBS processes.
2) Mg5 computes non zero amplitudes for the interference term between cHDD and every other interesting operator for all the VBS processes except for OSWW QCD production.
3) Mg5 computes non zero amplitudes for the interference term between every operators pair excluding cHDD for the OSWW QCD production.
A similar problem was found in this question: https:/
After a long discussion with one of the SMEFTsim developer (Ilaria Brivio) we are still puzzled about this behaviour that may be due to madrgraph internal computations.
I suppose that this is a know problem from the answers to the aforementioned launchpad question so what could one do in order to obtain a reliable simulation in you opinion?
Thank you for your time.
Best regards,
Giacomo
-------
[1]
Here i report the madgraph commands issued in order to generate events for the opposite sign WW QCD production:
import model SMEFTsim_
generate p p > e+ ve mu- vm~ j j QCD==2 SMHLOOP=0 NPprop=0 NP==1 NPcHDD^2==1 NPcHWB^2==1
add process p p > e- ve~ mu+ vm j j QCD==2 SMHLOOP=0 NPprop=0 NP==1 NPcHDD^2==1 NPcHWB^2==1
Output MadGraph:
import /afs/cern.
The import format was not given, so we guess it as command
import model SMEFTsim_
INFO: Restrict model SMEFTsim_
INFO: Run "set stdout_level DEBUG" before import for more information.
INFO: Change particles name to pass to MG5 convention
Defined multiparticle p = g u c d s u~ c~ d~ s~
Defined multiparticle j = g u c d s u~ c~ d~ s~
Defined multiparticle l+ = e+ mu+
Defined multiparticle l- = e- mu-
Defined multiparticle vl = ve vm vt
Defined multiparticle vl~ = ve~ vm~ vt~
Defined multiparticle all = g u c d s u~ c~ d~ s~ a ve vm vt e- mu- ta- ve~ vm~ vt~ e+ mu+ ta+ t b t1 t~ b~ t1~ z w+ z1 w1+ h h1 w- w1-
generate p p > e+ ve mu- vm~ j j QCD==2 SMHLOOP=0 NPprop=0 NP==1 NPcHDD^2==1 NPcHWB^2==1
INFO: Trying process: g g > e+ ve mu- vm~ g g NPprop=0 SMHLOOP=0 NP==1 QCD==2 NPcHDD^2==1 NPcHWB^2==1 @1
INFO: Trying process: g g > e+ ve mu- vm~ u u~ NPprop=0 SMHLOOP=0 NP==1 QCD==2 NPcHDD^2==1 NPcHWB^2==1 @1
INFO: Trying process: g g > e+ ve mu- vm~ u c~ NPprop=0 SMHLOOP=0 NP==1 QCD==2 NPcHDD^2==1 NPcHWB^2==1 @1
INFO: Trying process: g g > e+ ve mu- vm~ c u~ NPprop=0 SMHLOOP=0 NP==1 QCD==2 NPcHDD^2==1 NPcHWB^2==1 @1
INFO: Trying process: g g > e+ ve mu- vm~ c c~ NPprop=0 SMHLOOP=0 NP==1 QCD==2 NPcHDD^2==1 NPcHWB^2==1 @1
INFO: Trying process: g g > e+ ve mu- vm~ d d~ NPprop=0 SMHLOOP=0 NP==1 QCD==2 NPcHDD^2==1 NPcHWB^2==1 @1
INFO: Trying process: g g > e+ ve mu- vm~ d s~ NPprop=0 SMHLOOP=0 NP==1 QCD==2 NPcHDD^2==1 NPcHWB^2==1 @1
INFO: Trying process: g g > e+ ve mu- vm~ s d~ NPprop=0 SMHLOOP=0 NP==1 QCD==2 NPcHDD^2==1 NPcHWB^2==1 @1
…
Command "import /afs/cern.
"generate p p > e+ ve mu- vm~ j j QCD==2 SMHLOOP=0 NPprop=0 NP==1 NPcHDD^2==1 NPcHWB^2==1" with error:
NoDiagramException : No amplitudes generated from process Process: g/u/c/d/
command not executed: add process p p > e- ve~ mu+ vm j j QCD==2 SMHLOOP=0 NPprop=0 NP==1 NPcHDD^2==1 NPcHWB^2==1
command not executed: output OSWWQCD_
[2]
A snippet from the restriction card used to generate the interference between two operators for a pathological case
…
## INFORMATION FOR SMEFTCUTOFF
#######
Block SMEFTcutoff
1 1.000000e+03 # LambdaSMEFT
#######
## INFORMATION FOR SMEFT
#######
Block SMEFT
1 0 # cG
2 0 # cW
3 0 # cH
4 0 # cHbox
5 9.999999e-01 # cHDD
6 0 # cHG
7 0 # cHW
8 0 # cHB
9 9.999999e-01 # cHWB
10 0 # ceHRe
11 0 # cuHRe
12 0 # cdHRe
13 0 # ceWRe
14 0 # ceBRe
15 0 # cuGRe
16 0 # cuWRe
17 0 # cuBRe
18 0 # cdGRe
19 0 # cdWRe
20 0 # cdBRe
21 0 # cHl1
22 0 # cHl3
23 0 # cHe
24 0 # cHq1
25 0 # cHq3
26 0 # cHu
27 0 # cHd
28 0 # cHudRe
29 0 # cll
30 0 # cll1
31 0 # cqq1
32 0 # cqq11
33 0 # cqq3
34 0 # cqq31
35 0 # clq1
36 0 # clq3
37 0 # cee
38 0 # cuu
39 0 # cuu1
40 0 # cdd
41 0 # cdd1
42 0 # ceu
43 0 # ced
44 0 # cud1
45 0 # cud8
46 0 # cle
47 0 # clu
48 0 # cld
49 0 # cqe
50 0 # cqu1
51 0 # cqu8
52 0 # cqd1
53 0 # cqd8
54 0 # cledqRe
55 0 # cquqd1Re
56 0 # cquqd11Re
57 0 # cquqd8Re
58 0 # cquqd81Re
59 0 # clequ1Re
60 0 # clequ3Re
#######
## INFORMATION FOR SMEFTCPV
#######
Block SMEFTcpv
1 0 # cGtil
2 0 # cWtil
3 0 # cHGtil
4 0 # cHWtil
5 0 # cHBtil
6 0 # cHWBtil
7 0 # ceWIm
8 0 # ceBIm
9 0 # cuGIm
10 0 # cuWIm
11 0 # cuBIm
12 0 # cdGIm
13 0 # cdWIm
14 0 # cdBIm
15 0 # cHudIm
16 0 # ceHIm
17 0 # cuHIm
18 0 # cdHIm
19 0 # cledqIm
20 0 # cquqd1Im
21 0 # cquqd8Im
22 0 # cquqd11Im
23 0 # cquqd81Im
24 0 # clequ1Im
25 0 # clequ3Im
…
Question information
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