  The question of the nature of the dark matter in the Universe remains one of
the most outstanding unsolved problems in basic science. One of the best
motivated particle physics candidates is the lightest supersymmetric particle,
assumed to be the lightest neutralino - a linear combination of the
supersymmetric partners of the photon, the Z boson and neutral scalar Higgs
particles. Here we describe DarkSUSY, a publicly-available advanced numerical
package for neutralino dark matter calculations. In DarkSUSY one can compute
the neutralino density in the Universe today using precision methods which
include resonances, pair production thresholds and coannihilations. Masses and
mixings of supersymmetric particles can be computed within DarkSUSY or with the
help of external programs such as FeynHiggs, ISASUGRA and SUSPECT. Accelerator
bounds can be checked to identify viable dark matter candidates. DarkSUSY also
computes a large variety of astrophysical signals from neutralino dark matter,
such as direct detection in low-background counting experiments and indirect
detection through antiprotons, antideuterons, gamma-rays and positrons from the
Galactic halo or high-energy neutrinos from the center of the Earth or of the
Sun. Here we describe the physics behind the package. A detailed manual will be
provided with the computer package.
