A study for p + pbar-> Higgs or WW and other physics processes at Tevatron CM Energy 1.96TeV in NLO/NNLO calculation.


  • There are two ways to study NLO effact:
    • Generate Unweighted events: For Higgs, we can only use MC@NLO
    • Event Reweighting based on ratio of NLO to LO spectrum: It could be done by all generators. For Higgs, reweight based on two variables (pT, Rapidity)
  • For NNLO, we can only use Event Reweighting methods.

NLO Generator


  • MC@NLO is a standalone matrix element generator which matches Next-to-Leading-Order calculations of rates for QCD processes with a parton shower Monte Carlo event generator (HERWIG)
  • homepage:
  • Authors: Stefano Frixione and Bryan Webber
  • David Water's notes for MC@NLO, Oct 8 2003, html
  • CDF Note 7769: Documentation for the UserInfo? and UserInfoColl? classes -- useful for storing event weights.
  • Jason Galyardt's notes
  • Web Lecture by Stefano Frixione ( INFN ), Jun 24 2004, html

GR@PPA - GRace At Proton-Proton/Antiproton collisions

  • A GRACE -based event-generator framework for high energy hadron-collision interactions. The program can be embedded in a general-purpose event generator PYTHIA and HERWIG , to add initial- and final-state parton showers and the simulation of hadronization and decays.
  • homepage:
  • Authours: Soshi Tsuno, et. al.
  • W+jets study at CDF Tsuno's study
  • It can generate W/Z/WW/WZ/ZZ/ttbar/QCD/4bjets + njets

NLO Calculation

MCFM - Monte Carlo for FeMtobarn? processes

  • It can generate LO but not NLO unweighted events. It provides NLO calculations of Higgs/ttbar/Ewk/QCD processes
  • homepage:
  • Authors: John Campbell, Keith Ellis
  • Configuration:
    • technical.DAT: Use Spira's Higgs BR and Width results
 .true.          [spira]
  • Tips: Compiled MCFM to generate LO unweighted events in HBOOK ntuple format
   1. Compile mcfm with CERNLIB 
      A edit Install script
            set CERNLIB     =    /home/cdfsoft/products/cern/2004/Linux+2.4/lib
      B. Generate a makefile
      C. edit makefile
            NTUPLES = YES
      D. Compile, type make
         In the end, you'll see these messages.
          ----> MCFM compiled with its own PDFs only <----
          ----> MCFM compiled with optional n-tuple output <----        
   2. Generate n-tuple with mcfm. You can only generate LO unweighted events. Reseed to generate more statistics
       Edit input.DAT
       .true.         [creatent]  //create ntuple
       1089            [ij]         //different random number seed

   3. Convert hbook file to root file
       h2root [hbookfile] [root filename] 

NNLO Calculation

FEHiP? - Fully Exclusive Higgs Production

  • It cannot generate unweighted events but can calculate LO/NLO/NNLO cross sections of Higgs. Higgs can only decay through H->gamma gamma channels.
  • homepage:
  • Authors: C. Anastasiou , K. Melnikov and F. Petriello.
  • The ppbar collision is not implemented in the default source codes. Frank Petriello provides us three modified files for ppbar calculations. Shih-Chieh adds four new parameters for different Higgs (Pt, Rapidity) cuts.src codes
  • Edit constraint.F to implement event selection cuts. However, there are no histogram output from FEHiP? . We should consider implement by ourselves.
  • A comparison of Higgs Pt/Eta spectrum to Pythia is done
ggH160_Pt_20bin.gif ggH160_Rapidity.gif
  • The finner binning shows that there are negative contributions for lowest Pt bin. Why is that?


  • PDF used by Pythia@CDF
    'cteq5_l'              [pdlabel]
    4                         [NGROUP, see PDFLIB]
    46                       [NSET - see PDFLIB]
    MRST98.LHpdf  [LHAPDF group]
    1                         [LHAPDF set]


  • Higgs-boson pT in gluon fusion, by Russel P. Kauffman, Phys. Rev. D 44, 1415–1425 (1991), pdf: The mass dependent pT spectrum of Higgs.
  • Simulating the H→WW→llnunu Channel by Anne-Sylvie Giolo-Nicollerat, May 22 2006, pdf: Good talks about Higgs pT spectrum effacts
  • hep-ph/0604077: Combining Monte Carlo generators with next-to-next-to-leading order calculations: event reweighting for Higgs boson production at the LHC, Giovanna Davatz, Fabian Stoeckli, Charalampos Anastasiou, Guenther Dissertori, Michael Dittmar, Kirill Melnikov, Frank Petriello, JHEP 0607 (2006) 037: Event reweighting study by using FEHiP? , MC@NLO and Pythia
  • D0's simulation group: A good summary of MC generators

-- ShihChiehHsu - 23 Oct 2006

Topic attachments
I Attachment Action Size Date Who Comment
elsegz fehip_ppbar.tar.gz manage 5.0 K 2006/10/23 - 19:08 ShihChiehHsu FEHiP? Updated src codes for ppbar calculations
elseEXT ggH160_Pt_100bin manage 12.2 K 2006/10/23 - 18:54 ShihChiehHsu ggH160 Pt spectrum with 100 bins
gifgif ggH160_Pt_100bin.gif manage 9.5 K 2006/10/23 - 19:02 ShihChiehHsu ggH160 Pt spectrum with 100 bins
elseEXT ggH160_Pt_20bin manage 11.5 K 2006/10/23 - 18:57 ShihChiehHsu ggH160 Pt spectrum with 20 bins
gifgif ggH160_Pt_20bin.gif manage 9.9 K 2006/10/23 - 19:02 ShihChiehHsu ggH160 Pt spectrum with 20 bins
gifgif ggH160_Rapidity.gif manage 8.9 K 2006/10/23 - 18:48 ShihChiehHsu ggH Rapidity distribution at Tevatron
Topic revision: r2 - 2006/10/27 - 08:25:08 - BruceThayre
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