[Paper Review] Discovery Potential for SUGRA/SUSY at CMS

Stefano Villa|ArXiv.org|Sep 9, 2003

Particle physics theoretical and experimental studies1 references3 citations

TL;DR

This paper evaluates the discovery potential for supersymmetry (SUSY) at the CMS experiment at the Large Hadron Collider (LHC) within the mSugra (minimal Supergravity) framework. Using Monte Carlo simulations and fast detector reconstruction, it demonstrates that CMS can achieve a 5σ discovery reach of 2.6–3.0 TeV/c² for squarks and gluinos with 300 fb⁻¹ of integrated luminosity, and successfully reconstructs SUSY decay chains to measure sparticle masses with ~10% resolution at 10 fb⁻¹ luminosity.

ABSTRACT

The expected SUSY discovery potential of the CMS experiment at LHC is described, both in the MSSM and in the more constrained framework of mSugra, with emphasis on inclusive searches, the MSSM Higgs sector, and one example of complete reconstruction of a SUSY decay chain.

Motivation & Objective

• To assess the inclusive discovery reach of the CMS experiment for supersymmetry in the mSugra framework at the LHC.
• To evaluate the performance of CMS triggers for SUSY signals under both R-parity conserving and violating scenarios.
• To study the discovery potential for the MSSM Higgs sector, particularly the lightest Higgs boson decaying to b¯b.
• To demonstrate the feasibility of complete reconstruction of a SUSY decay chain, including mass measurements of squarks and gluinos.

Proposed method

• Used ISAJET 7.32 for SUSY signal generation and PYTHIA 5.7 for SM background simulation.
• Applied fast simulation via CMSJET 4.51 to model detector response and reconstruction efficiency.
• Optimized Level-1 and High-Level Triggers (HLT) using GEANT-based simulations for six mSugra benchmark points with varying m0 and m1/2.
• Implemented multivariate selection strategies based on Emiss_T > 200 GeV, jet ET > 40 GeV, and final-state topologies (0ℓ, 1ℓ, 2ℓOS, 2ℓSS, 3ℓ).
• Reconstructed the gluino-sbottom decay chain by associating the dilepton edge with the highest-ET b jet and fitting the sbottom and gluino invariant mass peaks.
• Used kinematic constraints from the χ⁰₂ decay to reconstruct the sbottom mass and infer the gluino mass, assuming Mχ⁰₁ ≈ Mχ⁰₂/2.

Experimental results

Research questions

• RQ1 What is the inclusive discovery reach of CMS for squarks and gluinos in the mSugra framework at 100 fb⁻¹?
• RQ2 Can CMS trigger systems effectively select SUSY events with high efficiency across diverse mSugra benchmark points?
• RQ3 What is the potential for discovering the lightest MSSM Higgs boson (h → b¯b) in SUSY cascade decays?
• RQ4 Can the full decay chain of a gluino-sbottom cascade be reconstructed to measure sparticle masses with high precision?

Key findings

• CMS achieves a 5σ discovery reach of 2.6–3.0 TeV/c² for squarks and gluinos in the mSugra framework with 300 fb⁻¹ of integrated luminosity.
• The inclusive discovery reach in the m0–m1/2 plane reaches up to 2.6–3.0 TeV/c² for squarks and gluinos, with minimal dependence on A₀, tan β, and sign(µ).
• With 10 fb⁻¹ of luminosity, the sbottom invariant mass peak is clearly visible, and the mass is reconstructed with a resolution better than 10%.
• The gluino mass is successfully reconstructed from the sbottom–b-jet association, also with a resolution of approximately 10%.
• The analysis of the dilepton invariant mass distribution shows a sharp kinematic edge at 16 GeV/c², enabling precise reconstruction of the χ⁰₂ decay kinematics.
• The discovery potential for the MSSM Higgs boson h → b¯b in SUSY cascades is demonstrated, with 5σ contours showing sensitivity up to 1200 GeV for m0 and m1/2 at 100 fb⁻¹.