4. How to spot strange decays
A schematic representation of the
interaction of a high-energy beam
(red) and a fixed target
(light blue), in which a
xi (dss) particle (dark blue)
is produced. The
xi particle decays into
a negative pion (purple) and
lambda (uds) particle, which is
shown as a dashed line because it
is neutral and cannot therefore be
seen directly. The lambda particle
subsequently decays into another
negative pion and a proton (orange).
The combination of a kink in the
path of a negatively charged particle
and the V-shaped decay into two
charged particles indicate that a
xi particle has decayed into a
lambda particle. The trajectories
of the charged particles are bent
by a magnetic field that is normal
to page. The charge and momentum of
these particles can be determined from
the curvature of the tracks.