BROOKHAVEN NATIONAL LABORATORY
                                 MEMORANDUM





Date:    27 March 2008
To:      ISAJET Users
From:    H. Baer, F.E. Paige, S.D. Protopopescu, X. Tata
Subject: ISAJET 7.78


ISAJET 7.78 is now available, replacing version 7.75. Several upgraded
features have been added.

First, we have added t1~ -> b W Z1~ decays, which were previously
missing. We have also improved the loop calculation t1~ -> c Z1~, which
often competes with the 3-body decay (thanks to A. Box for help on this
issue).

We have also improved the calculation of b -> s gamma decay in Isatools.
For full flavor structure in the decay, 137 MSSM RGEs must be solved
simultaneously.  These RGEs have been upgraded to two-loop ones, with
double precision runnning (thanks to A. Mustafayev). While BF(b -> s
gamma) is now more accurate, the calculation is slightly slower. Thus,
when running Isatools, the user is now prompted as to which calculations
are needed, so the slower b -> s gamma calculation can be avoided if the
user is not interested in the result.

We have implemented the Les Houches Event output capability.  By setting
the keyword WRTLHE to TRUE in the input file, parton showering,
hadronization and underlying event are turned off, so just the
production subprocess followed by (cascade) decays are allowed, and
color flow information is kept. Events are written in standard format to
an output file named isajet.lhe, which can be read in by programs such
as Pythia and Herwig, if alternative showering, hadronization and
underlying event algorithms are desired, which may include color flow
information.  For the Pythia read-in code, it is necessary to set the
lightest neutralino as stable by hand. This can be done via
      CALL PYGIVE('MDCY(C1000022,1)=0') .
Alternatively, if one has access to the PYDAT3 common block, one may set
      MDCY(PYCOMP(1000022),1)=0 .

We have also fixed some minor bugs in the initialization of the
neutralino relic density calculation by Isared, and an initialization
bug that affects sparticle spectra coming from successive runs of
Isasugra.  We fixed a bug in sparticle width assignments going from
IsaReD to CalcHEP.  Many thanks to Sasha Pukhov and Sasha Belyaev for
scrutinization of this code!

We have also changed the scale at which Yukawa couplings are evaluated
at in the relic density calculation, from Q = M(SUSY) to Q = 2M(Z1~}. In
Isatools, we now output the thermally averaged neutralino annihilation
cross section times velocity evaluated as v -> 0, which is useful for
indirect detection of dark matter calculations.

The new version can be obtained from
     http://www.hep.fsu.edu/~isajet/
or via AFS from
     /afs/cern.ch/user/p/paige/public/isajet
The version of isared.tar has also changed from 7.75.