4.6.16 SUBROUTINE ZAUCLU(MET, METPAR, PARSEL, PARLIS, NBJETS, ERROR) : Do jet clustering

By calling ZAUJSF, LUJETS is filled using the contents of ZATRS. Then LUCLUS is called, and /ZAJET/ is filled using /LUJETS/ after the call (as well as JETNB in /ZATRS/). ZAUJID is called to determine the true flavour of each jet, and the JETTYP variable of /ZAJET/ is filled

ARGUMENTS:

INPUT :

    MET : method ie.  JETSET MSTU(46), 1=LUCLUS, 4 = JADE.

          To do more complicated changes to LUCLUS, declare MET
          as an array in the calling program and assign the changes
          like this :
          If MET(1) = 0 then the rest of MET will be used
          as follows : for i even, MET(i) <> 0
          means that the MET(i+1) element will be
          assigned to MSTU(MET(i)).
          When the first even i with MET(i) = 0 is
          found, checking stops.
          Example :
          MET(1) = 0, MET(2) = 46, MET(3) = 4, MET(4) = 0 means
          that MSTU(46) will be set to 4, and no other changes
          to MSTU will be made.
    METPAR : parameters. If MET = 4, METPAR = y_cut, and
          if MET = 1, METPAR = d_join.

          Also here the same method can be used to do more
          intricate changes: Declare METPAR as an array. Then :
          If METPAR(1) = 0.0 then the rest of METPAR will be used
          to assign values to PARU, in the same way as MET is used
          to modify MSTU (see above).
          Example :
          METPAR(1) = 0.0, METPAR(2) = 44.0, METPAR(3) = 5.0,
          METPAR(4) = 0 means
          that PARU(44) will be set to 5.0, and no other changes
          to PARU will be made.
    PARSEL : Types of particles to use :
             PARSEL = 10*i + j
             j :
               0 : use measured values of seen tracks
               1 :  "    true      "    "    "     "
               2 :  "  measured    "    "   all    "
               3 :  "    true      "    "    "     "
             i :
               0 : charged and neutral
               1 : charged
               2 : charged and neutral, neutral from clusters
               3 : use parlis
    PARLIS : set of particles to use. Bit i set -> use this track.
             If neutral clusters are to be used, set bit
             TTRK + #of the cluster for the clusters to be used.
             PARLIS is only used if PARSEL = 30 + j

OUTPUT :

    NBJETS : number of jets found
    ERROR  : error code

IMPLICIT INPUTS:

    From /ZAEVT/ : MTRK, the total number of seen particles;
                   TTRK, the total number of particles.
    From /ZATRS/ : TRACK is used locally;
    From /ZASTE/ : MINJET, minimum number of jets to accept event;
                   MAXPR, number of events to print; EVT, current
                   event number; LUNPR, print-out unit.
    From /LUDAT/ : (filled by the call to LUCLUS) P, momenta and
                   K, various info, on jets and tracks.

IMPLICIT OUTPUTS:

    To /ZAEVT/ : NJET, the total number of jets.
    To /ZATRS/ : JETNB, jet number of track.
    To /ZAJET/ : PJET, jet momentum; THJET, jet theta; PHIJET, jet phi;
                 JETTYP, jet type; IJET, current jet number is used
                 locally.
    To /LUDAT1/ : MSTU(46), clustering method; MSTU(41), particles to
                 consider in clustering; PARU(45), y_cut.

CALLED BY :

ZAUCLU, jet CLUstering (see 4.6.16).

CALLED ROUTINE(S):

ZAUJSF (see 4.6.17)

(To do JetSet common Fill.)

ZUI2PI (see 4.7.2)

(To bring angle In range 0 to 2PI.)

ZAUJID (see 4.6.18)

(To find Jet IDentity.)

LUCLUS

(JETSET jet clustering routine.)

LULIST

(JETSET event listing routine.)

SIDE EFFECTS:

none

AUTHORS:

M. Berggren, UFRJ

CREATION DATE:

12-APR-1995