Neutralino reconstruction in supersymmetry with long-lived staus

TL;DR

This paper explores reconstructing neutralinos in a supersymmetric model with long-lived staus, focusing on collider signatures, background elimination, and mass measurement techniques.

Contribution

It introduces a method to fully reconstruct neutralinos decaying into taus and staus in a SUGRA scenario with long-lived charged particles.

Findings

Neutralino can be reconstructed over large parameter space.

Event selection criteria effectively reduce backgrounds.

A new method estimates stau mass from track curvature.

Abstract

We consider a supergravity (SUGRA) scenario, with universal scalar and gaugino masses at high scale, with a right-chiral neutrino superfield included in the spectrum. Such a scenario can have a lightest supersymmetric particle (LSP) dominated by the right sneutrino and a stau as the next-to lightest supersymmetric particle (NLSP). Since decays of all particles into the LSP are suppressed by the neutrino Yukawa coupling, the signal of supersymmetry consists in charged tracks of stable particles in the muon chamber. We demonstrate how a neutralino decaying into a tau and the stau-NLSP can be fully reconstructed over substantial areas in the SUGRA parameter space. We also suggest event selection criteria for eliminating backgrounds, including combinatorial ones, and use a new method for the extraction of the mass of the stau-NLSP, using its three-momentum as obtained from the curvature of the charged track.