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1 | \newpage |

2 | \section{Decay Table\label{DECAY}} |

3 | |

4 | ISAJET uses an external table of decay modes. Particles can be |

5 | put into the table in arbitrary order, but all modes for each particle |

6 | must be grouped together. The table is rewound and read in before each |

7 | run with a READ* format. Beginning with Version 7.41, the decay table |

8 | must begin with a comment of the form |

9 | \begin{verbatim} |

10 | ' ISAJET V7.41 11-JAN-1999 20:41:57' |

11 | \end{verbatim} |

12 | If this does not match the internal version number, a warning is |

13 | printed. After this initial line, each entry must have the form |

14 | \begin{verbatim} |

15 | IDENT,MELEM,CBR,ID1,ID2,ID3,ID4,ID5/ |

16 | \end{verbatim} |

17 | where IDENT is the code for the parent particle, MELEM specifies the |

18 | decay matrix element, CBR is the cumulative branching ratio, and |

19 | ID1,\dots,ID5 are the IDENT codes for the decay products. The |

20 | currently defined values of MELEM are: |

21 | \begin{center} |

22 | \begin{tabular}{cl} |

23 | \hline |

24 | MELEM &\quad Matrix Element \\ |

25 | \hline |

26 | 0 &\quad Phase Space \\ |

27 | 1 &\quad Dalitz decay \\ |

28 | 2 &\quad $\omega/\phi$ decay \\ |

29 | 3 &\quad $V-A$ decay \\ |

30 | 4 &\quad top decay: $V-A$ plus $W$ propagator \\ |

31 | 5 &\quad $\tau \to \ell \nu \bar \nu$ \\ |

32 | 6 &\quad $\tau \to \nu \pi$, $\nu K$ \\ |

33 | 7 &\quad $\tau \to \nu \rho$, $\nu a_1$ \\ |

34 | \hline |

35 | \end{tabular} |

36 | \end{center} |

37 | The parent IDENT must be positive; the charge conjugate mode is used |

38 | for the antiparticle. The values of CBR must of course be positive and |

39 | monotonically increasing for each mode, with the last value being 1.00 |

40 | for each parent IDENT. The last parent IDENT code must be zero. Care |

41 | should be taken in adding new modes, since there is no checking for |

42 | validity. In some cases order is important; note in particular that |

43 | quarks and gluons must always appear last so that they can be removed |

44 | and fragmented into hadrons. |

45 | |

46 | The format of the decay table for Versions 7.41 and later is |

47 | incompatible with that for Versions 7.40 and earlier. Using an |

48 | obsolete decay table will produce incorrect results. |

49 | |

50 | The decay table is contained in patch ISADECAY. |