D+ production discrepancy to FONLL and MC@NLO at forward-rapidity at 7TeV

Asked by Robert Hambrock

I'm computing the production spectrum of D+ at 7TeV with aMC@NLO, using Herwig++ as the event generator.
At mid rapidity, this is consistent with the results from FONLL (arXiv:1205.6344, figure 2), but at forward rapidity (arXiv:1205.6344, figure 3), my results for pT > 5GeV differ from FONLL by north of an order of magnitude. The plotted MC@NLO also diverge by a similar factor, but they do so only at far higher energies.

My results for B+ are fully consistent with FONLL.

To produce D+, I import the loop_sm-c_mass model to have massive charm, remove charm from the proton definition, generate 'p p > c c~ [QCD]', remove jet cuts on charm by adding 'maxjetflavor=3' to the run card (as suggested here: https://answers.launchpad.net/mg5amcnlo/+question/257415), and set beam energies and event generator.

Is there anything else I should add to my configuration to attain results consistent with FONLL, or are these discrepancies to be expected?

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marco zaro (marco-zaro) said :

Dear Robert,
I am not really an expert of this.
In principle what you do is ok, despite the fact that FONLL does a better resummation. However, you say that you get consistent results for the bottom quark.
Can you try to see if the same discrepancy is there when another shower (eg PYTHIA8) is used?

Let me know how it goes and sorry for not being able to be of much help



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