Open charm cross-section from the electron data

• Assuming all single electrons above the background are from charm i.e. neglecting other possible sources esp. thermal/direct virtual and real (converted) g

• Neglecting any modifications of nuclear PDFs (e.g. shadowing).

• The charm cross section per binary NN collision is obtained as:

  • Fitting the PYTHIA electron spectrum to the data for pT > 0.8 GeV/c
  • NN scaling:
  • TAA = nuclear overlap integral (NN integrated luminosity per event)
  • TAA=22.6 ± 1.6 mb-1 (central 0-10%)
  • TAA=6.2 ± 0.4 mb-1 (min. bias 0-92%)
  • scharm (central) = 380 ± 60 ± 200 mb
  • scharm (min bias) = 420 ± 33 ± 250 mb

• Dashed band = NLO pQCD

• Solid curves = PYTHIA

• Electron spectrum/cross-section

• consistent with pp scaled charm production

• (i.e. no nuclear or medium effects), but with

• large uncertainties !