AlphaQCD in gloun gloun fusion

Asked by ahh

Dear CH authors
In model file of hGG in calchep i found that alphaQCD(mh) is it the strong coupling "Alpha s = 0.1172"
Thanks
Ahmed

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Alexander Belyaev (alexander.belyaev) said :
#1

Dear Ahmed,
yes,
it is the strong coupling at the Mh scale.
Regards,
            Sasha

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ahh (ahh) said :
#2

Dear Dr Sasha
Thanks alot for your interest .
In fact , according to the model the higgs production at 14 TeV = 30 pb .
Is it consistent with the result here https://twiki.cern.ch/twiki/bin/view/LHCPhysics/HiggsEuropeanStrategy2012#SM_Higgs_production_cross_se_AN2 ??
Also when i try to disable the correction term " just try to calculate LO " it gives me 19.5 Pb .
So now the results :
LO = 19.5 pb , NLO = 30 pb , do you think this result is acceptable ????
Thanks again
Ahmed

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Alexander Belyaev (alexander.belyaev) said :
#3

Dear Ahmed,
your result, 30pb for NLO GG->H @ 14 TeV LHC is correct.
Indeed it is quite different from NNLO result which is 5o pb as quoted at the TWIKI page.

The point is that we have tuned GGH coupling to reproduce Higgs *decay* at NNLO level,
however we can not tune effective tree-level coupling tore reproduce very well NNLO GG->H
production since it is related to the energy-dependent correction due to the radiation of jets.

So, the bottom line is that at the moment 30pb is the best you can get from the effective GGH
coupling from CalcHEP

Sasha

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