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The exclusive mode

In this mode, the algorithm separates the `hard final state' from the soft `beam remnants' explicitly. Jets are defined in the hard final state by a stopping parameter $d_\mathit{cut}$ with dimensions of energy squared.
  1. $d_{kB}$ and $d_{kl}$ are defined as in section 2.1.
  2. Find $d_{min}$, the smallest value among the $d_{kB}$ and $d_{kl}$. If $d_{min} > d_\mathit{cut}$, all remaining objects in the event will be classified as jets, and the algorithm is complete.
  3. If a $d_{kl}$ is the smallest, $h_k$ and $h_l$ are combined into a single object with momentum $p_{(kl)}$ according to a user specified recombination scheme (parameter recom). If a $d_{kB}$ is the smallest, object $k$ is included in a `beam jet' and removed from the list. Go back to (2).
Note that the stopping parameter $d_\mathit{cut}$ defines the hard scale of the process ( $\Lambda_{QCD}^2 \ll d_\mathit{cut}\le s$, where $\sqrt s$ is the centre-of-mass energy). One can therefore think of the hard subprocess being factorised from the low-$p_\perp$ scattering fragments, which are thrown away into the beam jets. Instead of specifying the stopping scale $d_\mathit{cut}$, one can choose to stop merging when a given number of jets is reached.
next up previous
Next: Subjet analysis and mode Up: The algorithm Previous: The inclusive mode
Jonathan Couchman 2002-10-02