Figure 1:
Elements involved in threshold constraints. 

Figure 2:
Total outgoing particle energy in symmetric and asymmetric configurations. 

Figure 3:
An example of an upper and lower threshold. R is the region spanned by all and is the energy of the incoming particle. Where enters and leaves R are lower and upper thresholds, respectively. 

Figure 4:
Constraints on LV in QED at on a loglog plot. For negative parameters minus the logarithm of the absolute value is plotted, and region of width is excised around each axis. The constraints in solid lines apply to and both , and are symmetric about both the and the axis. At least one of the two pairs must lie within the union of the dashed bellshaped region and its reflection about the axis. Intersecting lines are truncated where they cross. 
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