Scaled Minimum Distance Algorithm

A loop runs over all pairs of tracks and finds the pair which has the smallest invariant mass M. If (M/EVIS^$\alpha$)² < $\sqrt{2(1-\cos 2\delta )}$, these 2 tracks are merged (i.e., 4-momenta added). The loop is then rerun over the new list of tracks which has lost 2 particles and gained the merged pair. When no remaining pair has a low enough mass, the track list contains a set of merged tracks. If these tracks have energies bigger than 2$\eta$Evis, they are called jets.

Input arguments:

ICLASS

described in 10.3.

ALPHA

Weight of track energies and Evis, in the calculation of the scaled mass. Pairs of tracks are merged if their scaled mass is smaller than $\sqrt{2(1-\cos 2\delta )}$.

DELTA

Half opening angle cut in degrees.

ETA

Cut on jet energies (fraction of 2Evis); only jets with energies > 2$\eta$Evis are kept.

EVIS

The visible energy of the event; if EVIS equals 0 , the visible energy is computed as the sum of the input particle energies.

Results:

NJETS

is the number of ``jets''.

'name'

Vectors containing 4-momenta of the jets.