  Supersymmetry plays a main role in all current thinking about superstring
theory. Indeed, many remarkable properties of string theory have been explained
using supersymmetry as a tool. So far, there has been no unbroken supersymmetry
observed in nature, and if nature is described by supersymmetry, it must be
broken. Supersymmetry may be broken spontaneously at any order of perturbation
theory or dynamically due to nonperturbative effects. To examine the methods of
supersymmetry breaking, special attention is given to discuss the normalization
of the ground state of the supersymmetric harmonic oscillator. This study
explains that perturbation theory gives incorrect results for both the
ground-state wave function and the energy spectrum and it fails to give an
explanation to the supersymmetry breaking.
