Dalitz plot

The Dalitz plot is a two-dimensional plot often used in <a href="/facts/Particle_physics/YgIuyj2t">particle physics</a> to represent the <a href="/facts/Statistical_frequency/FtFNmhDS">relative frequency</a> of various (kinematically distinct) manners in which the products of certain (otherwise similar) <a href="/facts/Particle_decay/3koAz34P">three-body decays</a> may move apart.
The <a href="/facts/Phase-space/qPe4Fq57">phase-space</a> of a decay of a <a href="/facts/Pseudoscalar/3ahEmnIW">pseudoscalar</a> into three spin-0 particles can be completely described using two variables. In a traditional Dalitz plot, the <a href="/facts/Coordinate_axis/Mtd0q4SP">axes</a> of the plot are the squares of the <a href="/facts/Invariant_mass/wNGXNBW6">invariant masses</a> of two pairs of the decay products. (For example, if particle A decays to particles 1, 2, and 3, a Dalitz plot for this decay could plot m212 on the x-axis and m223 on the y-axis.) If there are no angular correlations between the decay products then the distribution of these variables is flat. However symmetries may impose certain restrictions on the distribution. Furthermore, three-body decays are often dominated by <a href="/facts/Resonance/q7VLALUz">resonant</a> processes, in which the particle decays into two decay products, with one of those decay products immediately decaying into two additional decay products. In this case, the Dalitz plot will show a non-uniform distribution, with a peak around the mass of the resonant decay. In this way, the Dalitz plot provides an excellent tool for studying the <a href="/facts/Dynamics_(mechanics)/JLk81H71">dynamics</a> of three-body decays.
Dalitz plots play a central role in the discovery of new particles in current high-energy physics experiments, including <a href="/facts/Search_for_the_Higgs_boson/SGnvLGk0">Higgs boson research</a>, and are tools in exploratory efforts that might open avenues beyond the <a href="/facts/Standard_Model/LhVGf9ow">Standard Model</a>. 
<a href="/facts/Richard_Dalitz/wRnIYFsb">R.H. Dalitz</a> introduced this technique in 1953 to study decays of <a href="/facts/Kaon/Yn2w4QlQ">K mesons</a> (which at that time were still referred to as "tau-mesons"). It can be adapted to the analysis of four-body decays as well. A specific form of a four-particle Dalitz plot (for non-relativistic kinematics), which is based on a tetrahedral coordinate system, was first applied to study the few-body dynamics in atomic four-body fragmentation processes.

Dalitz plot open-in-new

Dalitz plot