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18 lines
1.2 KiB
18 lines
1.2 KiB
\midheading{$Z\gamma j$, production, processes 302, 307}
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\label{subsec:zgammajet}
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Processes {\tt 302} and {\tt 307} represent the production of a $Z$ boson (or virtual photon)
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in association with a real photon and at least one jet.
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The $Z/\gamma^*$ subsequently decays into
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either an $e^+ e^-$ pair ({\tt nproc=302}) or neutrinos ({\tt nproc=307}).
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Since these processes include a real photon and a jet, the cross section diverges
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when the photon or jet is very soft or in the direction of the beam.
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Thus in order to produce sensible results, the input file must supply values for both
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{\tt gammptmin} and {\tt gammrapmax}, and {\tt ptjetmin} and {\tt etajetmax}.
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Moreover, when the parameters {\tt zerowidth}
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and {\tt removebr} are set to {\tt .false.}, the decay $Z \to e^- e^+$ ({\tt nproc=302})
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will include photon radiation from both leptons, so that a non-zero $R(\gamma,\ell)_{min}$
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({\tt Rgalmin})
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should also be supplied. This will ensure that the cross section is well-defined.
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The calculation of processes {\tt 302} and {\tt 307} may be performed
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at NLO using the Frixione algorithm~\cite{Frixione:1998jh} or standard isolation.
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Anomalous couplings are not currently implemented for these processes.
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