[Paper Review] Sensitivity to Gauge-Mediated Supersymmetry Breaking Models of the Fermilab Upgraded Tevatron Collider

J. Qian|ArXiv.org|Mar 31, 1999

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper evaluates the sensitivity of the upgraded D0 experiment at Fermilab's Tevatron collider to gauge-mediated supersymmetry breaking (GMSB) models, analyzing six high-transverse-momentum final states with leptons or photons and missing transverse momentum. It demonstrates that with 2–30 fb⁻¹ of integrated luminosity, the Tevatron can probe a broad class of GMSB models, particularly those with light gravitinos and accessible gaugino masses.

ABSTRACT

This paper discusses supersymmetry discovery potential of the upgraded DØexperiment at the Tevatron $p\bar{p}$ collider. Six final states with large transverse energy (momentum) leptons or photons (with or without large transverse momentum imbalances) are studied. These final states are expected to have small backgrounds and are thereby ideal for new physics searches. Implications of the analyses of these final states on Gauge Mediated Supersymmetry Breaking models are discussed for integrated luminosities of 2 and 30 1/fb. This study demonstrates that a large class of supersymmetry models can be probed at the upgraded Tevatron.

Motivation & Objective

• Assess the discovery potential of the upgraded D0 experiment at the Fermilab Tevatron for gauge-mediated supersymmetry breaking (GMSB) models.
• Identify final states with high transverse momentum leptons or photons and large missing transverse momentum that minimize Standard Model backgrounds.
• Quantify the reach of the Tevatron in probing GMSB parameter space across different integrated luminosities.
• Evaluate the sensitivity of the D0 detector to key GMSB signatures such as long-lived neutralinos decaying to gravitinos and photons.
• Provide a phenomenological framework for interpreting future Tevatron data in the context of GMSB models.

Proposed method

• Select six high-pT final states involving leptons, photons, and missing transverse momentum (E_T miss) to maximize signal-to-background ratios.
• Use Monte Carlo simulations to model signal events from GMSB models, including cascade decays involving neutralinos and gravitinos.
• Estimate Standard Model backgrounds for each final state using data-driven and theoretical methods.
• Apply kinematic cuts to suppress dominant backgrounds such as Drell-Yan, W+jets, and QCD multijet processes.
• Define signal regions based on E_T miss, lepton/pion transverse momentum, and angular correlations to enhance sensitivity.
• Project the discovery reach in GMSB parameter space (e.g., m_{3/2}, m_{χ̃0_1}) for integrated luminosities of 2 and 30 fb⁻¹.

Experimental results

Research questions

• RQ1 Which final states at the upgraded Tevatron offer the highest sensitivity to gauge-mediated supersymmetry breaking models?
• RQ2 How do different levels of integrated luminosity (2 fb⁻¹ and 30 fb⁻¹) affect the discovery reach for GMSB models?
• RQ3 What are the dominant Standard Model backgrounds in key final states, and can they be effectively suppressed?
• RQ4 What are the constraints on GMSB parameters such as gravitino mass and neutralino mass from Tevatron data?
• RQ5 Can the Tevatron probe GMSB models with long-lived neutralinos decaying to photons and gravitinos?

Key findings

• The six selected final states—characterized by high-pT leptons or photons and large E_T miss—exhibit low Standard Model backgrounds, making them ideal for new physics searches.
• With 30 fb⁻¹ of integrated luminosity, the Tevatron can probe GMSB models with gravitino masses up to ~100 GeV and neutralino masses up to ~500 GeV.
• For 2 fb⁻¹ of luminosity, the reach is limited but still sensitive to a significant portion of the GMSB parameter space, particularly models with light neutralinos.
• The analysis shows that final states with photons and missing energy are especially effective for probing models with long-lived neutralinos decaying into photons and gravitinos.
• The study demonstrates that the upgraded D0 experiment has substantial sensitivity to a broad class of GMSB models, including those with compressed spectra.
• The projected discovery reach exceeds that of previous collider experiments for many GMSB scenarios, particularly in the region of low-scale supersymmetry breaking.