Gamma-ray Signal from Dark Matter Annihilation Mediated by Mixing Slepton

In order to reconcile the tension between the collider SUSY particle search and the dark matter relic density constraint, we free ourselves from the simplest CMSSM model and find a large parameter space in which a sub-TeV bino dark matter may comply with all the current experimental constraints. In this so-called incredible bulk region, dark matter mainly annihilates through the $t$ channel exchange of a mixing slepton into a leptonic final state. We have explored this proposal and studied the resultant spectrum feature. We are going to show that the line signal produced by the $\gamma\gamma$ and $\gamma Z$ final state will give some indications to the mixing angle and CP-violation phase of the slepton sector. On the other hand, internal bremsstrahlung (IB) feature will be easier to get observed by future experiments, with sensitivity around $10^{-29}\text{cm}^{3}/\text{s}$. Unlike some other models, our IB signal is dominated by the collinear limit of the final state radiation amplitude and shows a bump-like feature.