Some particles created in a particle collision will instantly decay into other particles. In these cases on has to look at the decay particles and use them to find out the nature of the initial particle.
The most common example is quarks, which according to the Standard Model does not exist on their own. A quark will instead create a jet of many particles. Such a jet of particles usually consists of ten or more particles. Quarks created in a collision are usually easy to identify since the jets are clearly visible in the detector.
Sometimes a quark emits a gluon (gluon radiation) at an early stage. Such a gluon will also create a jet of particles in the same way as the quarks.
Tau particles will also decay before they can be seen in the detector. A tau particle decays into 1 or 3 charged particles plus a number of neutral particles. If several neutral particles are created, the decay will result into a mini-jet resembling the quark jets. However, the mini-jet from the tau particle has fewer particles, less than ten. Often several neutrinos are created in the decays of tau particles. These will make the detected energy smaller than the collision energy.