Visualizing the mass and width spectrum of unstable particles

Abstract

Unstable particles are characterized by their mass and mass uncertainty, in addition to other kinematic and internal parameters. The mass uncertainty is called the width of the unstable particle and can be theoretically related to the particle lifetime by the Weisskopf–Wigner relation. Several graphical representations of the mass and width spectrum of unstable subatomic particles are presented. Such plots are useful tools for introducing students to the particle zoo and provide students an alternate way to organize conceptually what can seem like an overwhelming amount of data. In particular, such graphs highlight phenomenological features of unstable particles characteristic of different energy and time scales.