28496040 X3876_DDstar=TightCut

Decay of new narrow charged X+ state into DD* just at the threshold

• D_s1(2536)+ is used as proxy for X+
• mass of D_s1 is set to be 3.876 (just above D0D*+ threshold) and width of 2 MeV
• to get "charmonium-like" spectrum for charged X, a trick is used :
• X+ is generated in the decay of chi_c1(1P) -> X+ e-
• the mass of chi_c1 is set to be 3.890 GeV with a width of 2 MeV
• X+ decays into D0D+ and D+D0 pairs
• D* decays according to PDG into Dpi and Dgamma
• D0 decays into K- pi+
• D+ decays into K- pi+ pi+ usinng Dalitz decay model
• tight cuts for the D0/D+ mesons and all final state stable particles are applied
• two very nice tricks by Michael Wilkinson are used:
  • only charmonium production is activated for Pythia8
  • D+ lifetime cut for D0/D+ is applied via EvtGenDecayWithCutTool
• CPU performance is ~1.6seconds/event (655 seconds/400 events)
• integrated efficiency for generator-level cuts is (5.05+-0.36)% as reported in GeneratorLog.xml
• efficiency for D+ lifetime cuts is (38.48+-0.48)% (must be between 63 and 13%)
• efficiency for generator-level cuts is (10.66+-0.50)%

@ipolyako