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We're in the standard model

model = SM

Set up the process, restricting ourselves to up- and downquarks in the proton, together with gluons

alias parton = u:U:d:D:g
alias jet = parton

We could have added strange and charm jets (but we chose not to)

# alias jet = parton:s:S:c:C

Allow muons as well as electrons, but assume that we can identify charges and ignore antimuons and positrons

alias lepton = e1:e2
alias neutrino = n1:N1:n2:N2

Define the process, call O'Mega and compile the matrix element

process enj = parton, parton => lepton, neutrino, jet

Set masses of particles which are summed over to zero:

ms = 0
mc = 0
me = 0
mmu = 0

LHC design energy

sqrts = 14 TeV
beams = p, p => lhapdf { $lhapdf_file = "cteq5l.LHgrid" }

Define reasonable cuts and integrate the cross section(s) in order to initialize the phase space grids for similation

cuts = all Pt >= 10 GeV [jet:lepton]
integrate (enj) { iterations = 5:20000 }

Define title etc. as global variables, that will be used by PLOT

$description =
  "A WHIZARD 2.0 Example."
$ylabel = "$N_{\textrm{events}}$"

Allocate plots

$title = "$W$ Endpoint (``Jacobian Peak'') in $pp\to \ell\bar\nu j$"
$xlabel = "$p_T^\ell$/GeV"
histogram pt_lepton (0 GeV, 80 GeV, 2 GeV)
$title = "Jet-$p_T$ in $pp\to \ell\bar\nu j$"
$xlabel = "$p_T^j$/GeV"
histogram pt_jet (0 GeV, 80 GeV, 2 GeV)
$title = "Lepton Energy in $pp\to \ell\bar\nu j$"
$xlabel = "$E^\ell$/GeV"
histogram e_lepton (0 GeV, 160 GeV, 4 GeV)
$title = "Jet Energy in $pp\to \ell\bar\nu j$"
$xlabel = "$E^j$/GeV"
histogram e_jet (0 GeV, 80 GeV, 2 GeV)

Record transverse momenta and energies

analysis = record pt_lepton (eval Pt [extract index 1 [sort by Pt [lepton]]])
       and record pt_jet (eval Pt [extract index 1 [sort by Pt [jet]]])
       and record e_lepton (eval E [extract index 1 [sort by Pt [lepton]]])
       and record e_jet (eval E [extract index 1 [sort by Pt [jet]]])

Generate 1000 events

simulate (enj) { n_events = 1000 }

and write the events to file

compile_analysis { $out_file = "W-endpoint.dat" }
Last modified 8 years ago Last modified on Apr 7, 2011, 4:17:30 PM

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