Also found in: Wikipedia.
Pictorial representation in high-energy nuclear physics for data on the distribution of certain three-particle configurations. Many elementary-particle decay processes and high-energy nuclear reactions lead to final states consisting of three particles (which may be denoted by a, b, c, with mass values ma, mb, mc). Well-known examples are provided by the K-meson decay processes, Eqs. (1) and (2), and by the K- and -meson reactions with hydrogen, Eqs. (3) and (4).
If the three particles have kinetic energies Ta, Tb, and Tc (in the barycentric frame), Eq.
Not all points F within the triangle LMN correspond to configurations realizable physically, since the a, b, c energies must be consistent with zero total momentum for the three-particle system. With nonrelativistic kinematics and with equal masses m for a, b, c, the only allowed configurations are those corresponding to points F lying within the circle inscribed within the triangle, shown as (i) in the illustration. More generally, with relativistic kinematics, the limiting boundary is distorted as illustrated by the boundary curve (ii), drawn for the ω → 3π decay process, where the final masses are equal.