[u/mrichter/AliRoot.git] / ISAJET / doc / decay.doc

\newpage
\section{Decay Table\label{DECAY}}

      ISAJET uses an external table of decay modes. Particles can be
put into the table in arbitrary order, but all modes for each particle
must be grouped together. The table is rewound and read in before each
run with a READ* format. Beginning with Version 7.41, the decay table
must begin with a comment of the form
\begin{verbatim}
' ISAJET     V7.41   11-JAN-1999 20:41:57'
\end{verbatim}
If this does not match the internal version number, a warning is
printed. After this initial line, each entry must have the form
\begin{verbatim}
IDENT,MELEM,CBR,ID1,ID2,ID3,ID4,ID5/
\end{verbatim}
where IDENT is the code for the parent particle, MELEM specifies the
decay matrix element, CBR is the cumulative branching ratio, and
ID1,\dots,ID5 are the IDENT codes for the decay products. The
currently defined values of MELEM are:
\begin{center}
\begin{tabular}{cl}
\hline
MELEM   &\quad Matrix Element \\
\hline
0       &\quad Phase Space \\
1       &\quad Dalitz decay \\
2       &\quad $\omega/\phi$ decay \\
3       &\quad $V-A$ decay \\
4       &\quad top decay: $V-A$ plus $W$ propagator \\
5       &\quad $\tau \to \ell \nu \bar \nu$ \\
6       &\quad $\tau \to \nu \pi$, $\nu K$ \\
7       &\quad $\tau \to \nu \rho$, $\nu a_1$ \\
\hline
\end{tabular}
\end{center}
The parent IDENT must be positive; the charge conjugate mode is used
for the antiparticle. The values of CBR must of course be positive and
monotonically increasing for each mode, with the last value being 1.00
for each parent IDENT. The last parent IDENT code must be zero. Care
should be taken in adding new modes, since there is no checking for
validity. In some cases order is important; note in particular that
quarks and gluons must always appear last so that they can be removed
and fragmented into hadrons.

      The format of the decay table for Versions 7.41 and later is
incompatible with that for Versions 7.40 and earlier. Using an
obsolete decay table will produce incorrect results.

      The decay table is contained in patch ISADECAY.
Commit	Line	Data
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.