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14 lines
819 B
14 lines
819 B
\midheading{$W\gamma\gamma$ production, processes 370-371}
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\label{subsec:wgamgam}
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These processes represent the production of a $W$ boson which subsequently
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decays leptonically, in association with two real photons.
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Since this process includes real photons, the cross section diverges
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when the photon 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}. Moreover, when the parameters {\tt zerowidth}
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and {\tt removebr} are set to {\tt .false.} the decay $W \to \ell \nu$ will include
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photon radiation from the lepton, so that a non-zero {\tt R(photon,lept)\_min} should
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also be supplied. This will ensure that the cross section is well-defined.
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These processes may be computed at leading order only.
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