= Explicit versus spontaneous supersymmetry breaking
Explicit breaking changes the action so that the former <supercharges> are not conserved symmetries of the full Hamiltonian. Spontaneous breaking preserves the action and algebra but has a vacuum that some <supercharge> does not annihilate. <Energy positivity in global supersymmetry> then implies positive vacuum energy density, and a <Goldstino> accompanies the broken symmetry. That exact-algebra energy argument does not apply to an arbitrarily explicitly broken Hamiltonian. The physical particle spectrum in a broken vacuum need not assemble into the finite equal-mass <supermultiplets> of an invariant vacuum.
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