Longevity of supersymmetric flat directions

Abstract

We examine the fate of supersymmetric flat directions. We argue that the non-perturbative decay of the flat direction via preheating is an unlikely event. In order to address this issue, first we identify the physical degrees of freedom and their masses in presence of a large flat direction VEV (Vacuum Expectation Value). We explicitly show that the (complex) flat direction and its fermionic partner are the only light {\it physical} fields in the spectrum. If the flat direction VEV is much larger than the weak scale, and it has a rotational motion, there will be no resonant particle production at all. The case of multiple flat directions is more involved. We illustrate that in many cases of physical interest, the situation becomes effectively the same as that of a single flat direction, or collection of independent single directions. In such cases preheating is not relevant. In an absence of a fast non-perturbative decay, the flat direction survives long enough to affect thermalization in supersymmetric models as described in hep-ph/0505050 and hep-ph/0512227. It can also ``terminate'' an early stage of non-perturbative inflaton decay as discussed in hep-ph/0603244.Comment: 9 revtex pages, v3: expanded discussion on two flat directions, minor modifications, conclusions unchange