# Supersymmetry O'Raifeartaigh model negative fermionic masses

1. Jan 27, 2008

### Eisenhorn

Greetings,

I calculated a basic O'Raifeartaigh model, using the following potential
$$f = \lambda Y_1 (X^2 - M^2) + \mu Y_2 X$$, where $$Y_1$$, $$Y_2$$ and $$X$$ are chiral superfields. Assuming that the vacuum expectation value of $$y_1$$ is zero (where $$y_1$$ is the scalar component of $$Y_1$$), I get a fermionic mass matrix like
$$\left(\begin{array}{ccc}0 & 0 & 0 \\0 & 0 & \mu \\0 & \mu &0\end{array}\right)$$.

My problem is that the eigenvalues of this fermionic mass matrix are $$\mu$$ and $$-\mu$$, and I dont understand the later. Why do I get a negative mass and how can I interpet it?

Eisenhorn.