Kinematic Edges with Flavor Splitting and Mixing

TL;DR

This paper investigates how lepton flavor dependence affects the kinematic edges in invariant mass distributions in supersymmetric models, proposing methods to extract superpartner masses despite slepton mixing and flavor effects.

Contribution

It introduces a novel approach to extract invariant mass endpoints considering slepton flavor splitting and mixing, improving mass measurements in supersymmetry.

Findings

Multiple edges appear due to slepton mass splitting and mixing.

Flavor subtraction can dilute the signal, but flavor-added distributions remain robust.

The method effectively extracts slepton flavor parameters in example scenarios.

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.