The model can not handle loop processes.

[leeh]

Dear SARAH authors,

I have a problem in calculating the Drell-Yan process at NLO using a specific model, which is a simple extension of type II 2HDM, generated by SARAH and SPheno. I already asked this question to the MadGraph authors and got this answer:
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Dear MG experts,

I am having trouble calculating the Drell-Yan process at NLO using a specific model. The model is a simple extension of type II 2HDM with one singlet flavon, which we generated through SARAH and SPheno. To calculate the Drell-Yan process at NLO, I utilized the UFO file generated by SARAH for the model, but encountered an error in the process:

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load MG5 configuration from input/mg5_configuration.txt
fastjet-config does not seem to correspond to a valid fastjet-config executable (v3+). We will use fjcore instead.
Please set the 'fastjet'variable to the full (absolute) /PATH/TO/fastjet-config (including fastjet-config).
MG5_aMC> set fastjet /PATH/TO/fastjet-config

set ninja to /home/leeh/MG5_aMC_v3_4_1/HEPTools/lib
set collier to /home/leeh/MG5_aMC_v3_4_1/HEPTools/lib
set lhapdf to /home/leeh/MG5_aMC_v3_4_1/HEPTools/LHAPDF-6.5.3/LHAPDF_install/bin/lhapdf-config
set lhapdf to /home/leeh/MG5_aMC_v3_4_1/HEPTools/LHAPDF-6.5.3/LHAPDF_install/bin/lhapdf-config
Using default text editor "vi". Set another one in ./input/mg5_configuration.txt
Using default eps viewer "evince". Set another one in ./input/mg5_configuration.txt
Using default web browser "firefox". Set another one in ./input/mg5_configuration.txt
Loading default model: sm
INFO: Restrict model sm with file models/sm/restrict_default.dat .
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- ve~ vm~ vt~ e+ mu+ t b t~ b~ z w+ h w- ta- ta+
MG5_aMC>import model THDM_Global_UFO/ -modelname
impossible to set default multiparticles vl~ because No particle ve~ in model
Kept definitions of multiparticles p / j / l+ / l- / vl unchanged
Removed obsolete multiparticles vl~ / all
Defined multiparticle all = g ah2 a nu1 nu2 nu3 d1 d2 d3 d4 d5 u1 u2 u3 u4 u5 d1bar d2bar d3bar d4bar d5bar u1bar u2bar u3bar u4bar u5bar h1 h2 h3 ah3 hm2c z wmc hm2 wm e1 e2 e3 e4 e5 nu4 nu5 nu6 nu7 e1bar e2bar e3bar e4bar e5bar
MG5_aMC>generate p p > e2 e2bar [noborn=QCD]
The current model THDM_Global_UFO does not allow to generate loop corrections of type ['QCD'].
Command "generate p p > e2 e2bar [noborn=QCD]" interrupted with error:
InvalidCmd : The model THDM_Global_UFO cannot handle loop processes

After some searches, I discovered that there are already some similar cases, and I believe this is a closely related one.

https://answers.launchpad.net/mg5amcnlo ... ion/704535

Based on the response provided in the inquiry, it appears that rewriting the Lagrangian and parameters in FeynRules with the NLOCT package is necessary to calculate loop processes. However, I am wondering if the same approach can be applied to our UFO file or if there is a way to enable loop process calculations within SARAH for our specific UFO file.

Many thanks in advance
Huchan Lee
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Hi,

I guess that this is a question for Sarah author.
I would be afraid to say that this is not possible while this is actually just me not aware enough in SARAH capabilities.

Cheers,

Olivier
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As I asked in my question, what I want to know is if there is a way to enable loop process calculations within SARAH for our specific UFO file.

Many thanks in advance.
Huchan

[porod]

Hi,

with the current implementation this not possible.

Best, Werner