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28 lines
1.8 KiB
28 lines
1.8 KiB
\midheading{$W+t{\bar t}$ processes 500--516}
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\label{subsec:wttdecay}
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These processes represent the production of a $W^\pm$ boson which subsequently
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decays leptonically, in association with a $t{\bar t}$ pair. In all except processes
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{\tt 500} and {\tt 510} the decays of the top and anti-top quark are included.
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Processes {\tt 501,502} and {\tt 511,512} refer to the semileptonic decay of the top and antitop quarks,
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with the latter process in each pair giving the radiation in the decay of the top and antitop.
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Process {\tt 503} ({\tt 513}) refers to the semileptonic decay of the top (antitop)
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and the hadronic decay of the antitop (top). Processes {\tt 506}({\tt 516}) gives the semileptonic
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decay of the antitop(top) and the hadronic decay of the top(antitop). Processes {\tt 506}({\tt 516})
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do not give same sign lepton events, so they may be of less phenomenological importance. For this reason
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we have not yet included radiation in the decay for these processes.
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For processes {\tt 503}, {\tt 506}, {\tt 513}
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and {\tt 516} the default behaviour is that the hadronic decay products
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are clustered into jets using the supplied jet
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algorithm parameters, but no cut is applied on the number of jets.
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This behaviour can be altered by changing the value of the
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variable {\tt notag} in the file {\tt src/User/setnotag.f}.
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The top quarks are always
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produced on-shell, which is a necessity for a gauge invariant result
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from this limited set of diagrams, but all spin correlations are included.
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Switching {\tt zerowidth} from {\tt .true.} to {\tt .false.} only affects
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the $W$ bosons (both the directly produced one and from the top quark decay).
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Processes {\tt 501} and {\tt 511} may be run at NLO with the option {\tt todk},
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including radiation in the decay of the top quark, see section \ref{subsec:ttbar}.
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