MadOnia Low Production Rate of 3S1(8), 1S0(8)

Asked by Reggie Bain on 2014-11-07

Hi,

I am having a problem with the process gg>gcc~[3S18to9940003] (where 9940003 is for showering with Pythia 8) for producing a 3S1(8) J/psi. When requesting 50,000 events I get 11,133. Here are the relevant pieces of information from my Cards:

proc_card.dat
gg>gcc~[3S18to9940003]
QCD=99
QED=2

run_card.dat
 0 = ickkw ! 0 no matching, 1 MLM, 2 CKKW matching
 45 = ptj ! minimum pt for the jets
 45 = ptonium ! minimum pt for the quarkonium states
 0.4 = drjj ! min distance between jets
 3 = mmjj ! min invariant mass of a jet pair
 0 = xqcut ! minimum kt jet measure between partons

param_card.dat
         4 1.60000000E+00 # charm pole mass
Block LDME
        1 0.3866666E+00 # 1S01
        2 4.97E-02 # 1S08
        3 1.32E+00 # 3S11
        4 2.24E-03 # 3S18
        5 0.107429E+00 # 3P01
        6 1.61E-02 # 3P08
        7 0.322288E+00 # 3P11
        8 1.61E-02 # 3P18
        9 0.537147E+00 # 3P21
        10 1.61E-02 # 3P28

Similarly, when I run gg>ggcc~[1S08to9941003] with the same run conditions I get only 1649/50000 events.

In general, I am looking for 2 jet events where 1 jet contains the J/psi. I shower on the unweighted_events.lhe file using Pythia 8 and then use Rivet to reconstruct the J/psi (from two muons) and jets using the anti-kT algorithm. Since I wanted rivet to handle the jet algorithms, I have left ickkw at 0.

What might be the source of this terribly low event rate?

Thank you,

Reggie

Question information

Language:
English Edit question
Status:
Open
For:
MadGraph5_aMC@NLO Edit question
Assignee:
Pierre Artoisenet Edit question
Last query:
2014-11-07
Last reply:

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