[Rivet] D0_1996_S3324664

[Lars Sonnenschein]

Hello Frank
apart of the jet algorithm details mentioned below
the Run I cone does not use the energy scheme and does not look at 
midpoints as the Run II cone does. Therefore this algorithm is not 
infrared safe.

Anyway, I will dig out the original code from D0 if possible
and let you know

	Lars

On Thu, 22 Jan 2009, Frank Siegert wrote:

> This is another interesting analysis, which I would like to implement:

  http://hepdata.cedar.ac.uk/hepdata/hepreac/3324664
  http://durpdg.dur.ac.uk/cgi-bin/spiface/hep/www?irn+3324664

Has anybody used a jet finder similar to the described one yet, or have 
any hint on how complicated it will be to implement this?

"Jet reconstruction was performed using an iterative
fixed cone algorithm. First, the list of calorimeter towers
with ET > 1 GeV (seed towers) was sorted in descending
order. Starting with the highest ET seed tower, a preclus-
ter was formed from all calorimeter towers with R < 0.3,
where R = sqrt(??² + ??²) was the distance between tower
centers. If a seed tower was included in a precluster, it
was removed from the list. This joining was repeated un-
til all seed towers become elements of a precluster. After
calculating the ET weighted center of the precluster, the
radius of inclusion was increased to 0.7 about this cen-
ter with all towers in this cone becoming part of the jet.
A new jet center was calculated using the ET weighted
tower centers. This process was repeated until the jet
axis moved less than 0.001 in ?-? space between itera-
tions. The final jet ET was defined as the scalar sum of
the ET of the towers; its direction was defined using the
DØ jet algorithm (10), which differs from the Snowmass
algorithm (11). If any two jets shared more than half of
the ET of the smaller ET jet, the jets were merged and
the jet center recalculated. Otherwise, any ambiguities
in the overlap region were resolved by assigning the en-
ergy of a given cell in the shared region to the nearest
jet."

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Lars Sonnenschein    
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