Prospects for use of flavored kT jet finding

Asked by Marjorie Shapiro

A group of us on ATLAS are currently working on a measurement of W+c production with the goal of constraining the strange pdf. We measuring the opposite sign minus the same sign (OS-SS) Wc cross sections (to remove W+ccbar and W+bbar contributions) and are modeling the signal using MG5_aMC@NLO with the process cards such as:

import model loop_sm-ckm_c_mass
define p = g u d s u~ d~ s~
generate p p > mu+ vm c~ [QCD]

We have successfully run this process both for FO and showering with Pythia8 and with Herwig7 and get good agreement between the predictions for the OS-SS cross sections obtained this way and with those obtained using FxFx W+jets (with up to 3 jets).

Recently, an NNLO calculation of the process has been completed ( Although that paper presents results for 7 TeV (to compare to the last published ATLAS results) we are in contact with the authors to obtain cross sections at NLO and NNLO for 13 TeV differential distributions and we would like to compare those calculations to the NLO results obtained with aMC@NLO. Eventually, we hope to include ATLAS data in PDF fits using the APPLgrid aMC@NLO interface (with the possibility of using a table of correction factors to reweight from NLO to NNLO).

The NNLO calculation is done using a flavored kT jet finding algorithm. I was wondering if there is any prospect for using flavored kT with aMC@NLO either for FO or for parton shower calculations?


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marco zaro (marco-zaro) said :

Hi Marjorie,
thank you for posting your question.
In principle, the cuts and analyses are completely free to be modified by the user, therefore one can edit them in order to apply whatever jet algorithm they want.
However, at present, the wrappers to fastjet we have do not allow to pass the flavour of the particles to be clustered, thus I think it is not going to be trivial to have what you ask for, at least at fixed order. With the shower, once you produce the HepMC file, you can analyse it with whatever tool/framework you like most.
Let me know if this helps.



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