Measuring sparticle masses in non-universal string inspired models at the LHC

TL;DR

This work investigates the viability of string/M-theory motivated SUSY spectra at the LHC and introduces an optimized non-universal string model (O1) designed to avoid dangerous CCB/UFB minima. By extending model-independent endpoint methods and adding a novel M_T2-based constraint, the authors demonstrate that squark, slepton, and neutralino masses can be extracted with sufficient precision to distinguish O1 from a closely related SUGRA point (S5) despite near-degenerate spectra. The approach relies on a network of kinematic edges from sequential and branched decay chains, supplemented by M_T2 and Z/Higgs-branched channels, with detector-level simulations (ATLAS-like) and 100 fb⁻¹ of data. The results indicate that model-independent sparticle mass reconstruction is feasible for non-universal, string-inspired models and that the developed methods can generalize to other non-universal scenarios, offering a practical pathway to differentiate string-derived SUSY phenomenology from conventional SUGRA expectations.

Abstract

We demonstrate that some of the suggested five supergravity points for study at the LHC could be approximately derived from perturbative string theories or M-theory, but that charge and colour breaking minima would result. As a pilot study, we then analyse a perturbative string model with non-universal soft masses that are optimised in order to avoid global charge and colour breaking minima. By combining measurements of up to six kinematic edges from squark decay chains with data from a new kinematic variable, designed to improve slepton mass measurements, we demonstrate that a typical LHC experiment will be able to determine squark, slepton and neutralino masses with an accuracy sufficient to permit an optimised model to be distinguished from a similar standard SUGRA point. The technique thus generalizes SUSY searches at the LHC.