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31 lines
1.6 KiB
31 lines
1.6 KiB
\midheading{Di-boson production, processes 61--89}
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\label{subsec:diboson}
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These processes represent the production of a diboson pair $V_1 V_2$,
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where $V_1$ and $V_2$ may be either a $W$ or $Z/\gamma^*$.
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All the processes in this section may be calculated at NLO with the exception
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of {\tt nproc=69}. There are various
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possibilities for the subsequent decay of the bosons, as specified in the
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sections below. Amplitudes for the $V_1 V_2$ process at $O(\alpha_s)$
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are taken from ref.~\cite{Dixon:1998py}.
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We also include singly resonant diagrams at NLO for all processes
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in the case {\tt zerowidth = .false.}.
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For more details on this calculation, please see
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Refs.~\cite{Campbell:1999ah,Campbell:2011bn}.
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For processes {\tt 62}, {\tt 63}, {\tt 64}, {\tt 65}, {\tt 74}
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and {\tt 75} the default behaviour is that the hadronic decay products
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of the bosons 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 \verb|src/User/setnotag.f|.
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Calculations of processes {\tt 61}, {\tt 71}, {\tt 76}, {\tt 81} and {\tt 82}
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can be performed at NLO by subtraction, zero-jettiness slicing and $q_T$-slicing.
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They can be computed at NNLO using zero-jettiness slicing and $q_T$-slicing,
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as described in 'Non-local slicing approaches for NNLO QCD in MCFM',\cite{Campbell:2022gdq}.
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For processes {\tt 61}, {\tt 81} and {\tt 86} the NNLO corrections
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include glue-glue initiated box diagrams which first contribute at order $\alpha_s^2$.
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Two loop results for virtual diagrams at $O(\alpha_s^2)$ are taken from \cite{Gehrmann:2015ora}.
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