Jet Algorithms

Several jet algorithms exist. The calling sequence for those is

      double precision P(4,*), YCUT, SCALE, VEC(4,*)
      integer          NPA, IRECOM, NUM

      call <algo>jet(P,NPA,YCUT,SCALE,I,IRECOM,NUM,VEC)

where <algo> is replaced by the name of the algorithm (i.e. one of jade, kt).

The common arguments are :

• P the input particles,
• NPA the number of input particles,
• VEC the output jet axes and energies,
• NUM the number of jets and
• IRECOM gives the recombination scheme for two particles (see the description of the support routine vadd in section 5.4 for more details).

The remaining arguments are algorithm dependent. Please refer to the individual manual. The basic idea is, that SCALE corresponds to a scaling factor and YCUT corresponds to a cut value. This is for example the scale for the invariant mass and the maximum mass over scale value for the jade algorithm and the minimum jet E_t and the maximal cone radius for the cone algorithm. I is an additional input value with no predefined meaning.

For the KTCLUS package, a slightly different calling sequence is used :

      SUBROUTINE KTINCJET(P,NPA,PTMIN,NUM,V)

      DOUBLE PRECISION P(4,*),V(4,*),PTMIN
      INTEGER NUM,NPA

      SUBROUTINE KTCLUSJET(P,NPA,SCALE,YCUT,NUM,V)

      DOUBLE PRECISION P(4,*),V(4,*),SCALE,YCUT
      INTEGER NUM,NPA

where the arguments correspond to the arguments explained in the beginning of the section.