EXOTIC - a heavy fermion and excited fermion Monte Carlo generator for e+e- physics. R. Tafirout, G. Azuelos.

Title of program: EXOTIC
Catalogue identifier: ADLJ
Ref. in CPC: 126(2000)244
Distribution format: gzip file
Operating system: HPUX, Solaris, VAX/VMS, IRIX, Linux
High speed store required: 2.5MK words
Number of bits in a word: 32
Number of lines in distributed program, including test data, etc: 5508
Programming language used: Fortran
Computer: HP 9000/700 series

CPC Program Library subprograms used:

 Cat. Id.  Title                             Ref. in CPC
 ACTU      PYTHIA 5.7 AND JETSET 7.4          82(1994)74                     
 ACTA      PHOTOS version 2.0                 79(1994)291                    

Nature of physical problem:
Cross section and event generation for e+e- -> FFbar (pair production), and e+e- -> fbarF (single production) of heavy or excited fermions which decay into their light standard fermion partner and a gauge boson. The processes generated account for full spin correlations in the production and decay processes, with inclusion of initial and final state radiation (see chapter 3 for details). An interface to JETSET allows fragmentation and hadronization of final quarks.

Method of solution
For fast Monte Carlo generation of unweighted events, some distributions are calculated once, then sampled. Event sampling is done only at the last stage, after evaluation of the total polarized differential cross section according to its maximum value.

Restrictions on the complexity of the problem
The program is specifically designed for high energy e+e- collisions, i.e. at LEP 2 and NLC. The program does not include cascade decays, where a heavy fermion decays into a lighter heavy fermion, which in turn decays also into a light standard fermion and a gauge boson.

Typical running time
With initial state radiation and full spin correlations, the generation of 5000 unweighted events e+e- -> FFbar without fragmentation and hadronization of final quarks takes on average 205 seconds in CPU time on an HP 9000/755 (275 seconds when including fragmentation and hadronization).

Unusual features of the program
REAL*8 and COMPLEX*8 declarations are used. For some processes, the program uses the GENBOD routine, from the CERN program library [4] (RAMBO is not efficient when outgoing particles have masses greater than the half of the available energy, which could be the case for a charged heavy lepton decaying into a neutral heavy lepton and a virtual or real W boson). The random number generator used is RANMAR from the CERN Program Library.


 [1] R. Kleiss, W.J. Sterling and S.D. Ellis, Comp. Phys. Comm.          
     40 (1986) 359.                                                      
 [2] T. Sjostrand, Comp. Phys. Comm. 82 (1994) 74.                       
 [3] E. Barberio and Z. Was, Comp. Phys. Comm. 79 (1994) 291.            
 [4] CERN Program Library, CN Division, CERN, Geneva.