Kinematic Edges with Flavor Splitting and Mixing

Abstract

The kinematic edges of invariant mass distributions provide an important tool for the possible measurements of superpartner masses in supersymmetric models with a neutralino LSP. We examine the effect of lepton flavor dependence on the kinematic endpoints of the di-lepton invariant mass distribution, with the leptons being electrons and muons. In the presence of slepton mass splitting and mixing, each of these distributions exhibits multiple edges, which are likely to be close. Furthermore, flavor subtraction, which is usually employed to eliminate backgrounds, dilutes the signal. We propose to extract the endpoints from the flavor-added distribution, which is insensitive to the slepton mixing. We also discuss the extraction of the slepton flavor parameters in such scenarios. To demonstrate our results, we use an example with a small slepton mass splitting of 3 GeV leading to a 6 GeV edge splitting, at both small mixing and large mixing.