Bogomol'nyi–Prasad–Sommerfield bound

In the classical bosonic sector of a supersymmetric field theory, the Bogomol'nyi–Prasad–Sommerfield (BPS) bound (named after Evgeny Bogomolny, M.K. Prasad, and Charles Sommerfield) provides a lower limit on the energy of static field configurations, depending on their topological charges or boundary conditions at spatial infinity. This bound manifests as a series of inequalities for solutions of the classical bosonic field equations.

Source: Wikipedia — Bogomol'nyi–Prasad–Sommerfield bound (CC BY-SA 4.0)