Relic abundance of light photinos

We solve the coupled Boltzmann equation for the system of light photinos interacting with pions and $R^0$’s (the gluon-gluino bound state) to determine the relic abundance of light photinos in the light gaugino scenario. Cosmology bounds the ratio $r$ of the $R^0$ mass to the $\tilde{\gamma }$ mass to be less than about $1.8$. We also use a model Lagrangian embodying crossing symmetry between the $R^0\leftrightarrow \tilde{\gamma }\pi \pi$ and $R^0\pi \leftrightarrow \tilde{\gamma }\pi$ reactions to identify cosmologically favored regions of $R^0$ lifetime as a function of $R^0$ and $\tilde{\gamma }$ masses.