MadGraph5_aMC@NLO

SMEFTatNLO model insanely large cross section value

Asked by Wei He

I use SMEFTatNLO-LO model to run processes. And recently I got super high cross section value if I set NP = 2. there's no such a problem if I set np=0. I tried different versions and I tried to reinstall the model. But it doesn't work.

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Olivier Mattelaer
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Wei He (heweiii) said : 		#1

I know if I set np=2 the cross section value would be larger than np=0. But this is way too large, it's impossible theoretically.

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Olivier Mattelaer (olivier-mattelaer) said : 		#2

Well did you change the value of the coupling?
I do not know the default value for that model, but many SMEFT model use coupling=1 as their default, which is indeed already excluded experimentally (and leading to large cross-section).

If you need more help, the best might be to contact the authors of that model.

Cheers,

Olivier

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Wei He (heweiii) said (last edit ): 		#3

Hi, Thank you for your reply. I did changed the paramcard. I set bottomyukawa in configuration to true. And I add 18 cbp and 5 ymb to the paramcard. Cause I need to decay higgs.

Regard

Wei

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Best Olivier Mattelaer (olivier-mattelaer) said : 		#5

Sorry I do not know what cdp is meaning, if this is an effective coupling this sounds a large value. But as said above, you might need to contact the author of the model, they would know better than me.

Cheers,

Olivier

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Wei He (heweiii) said : 		#6

Thanks Olivier Mattelaer, that solved my question.

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Wei He (heweiii) said : 		#7

Another bug that I encountered is : command "generate events run 02" interrupted with errorValueError : could not convert string to float: b' 500_pts_failed_stop_executationn'lease report this bug on https://bugs.launchpad.net/mg5amcnlo

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Olivier Mattelaer (olivier-mattelaer) said : 		#8

please report it to https://bugs.launchpad.net/mg5amcnlo
and attach the debug file.
It might be an issue when converting our code from python2 to python3. But more likely an issue that the loop that you try to compute are numerically unstable and not computable.

Thanks,

 Olivier