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0795afa3 | 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. |