[Paper Review] Entangled System of Squarks from the Third Generation at the Large Hadron Collider

AseshKrishna Datta, Saurabh Niyogi|arXiv (Cornell University)|Nov 1, 2011

Particle physics theoretical and experimental studies45 references3 citations

TL;DR

This paper proposes a signature-based search for third-generation squarks (stop and sbottom) at the Large Hadron Collider using entangled final states from pair production. By analyzing decay chains involving top quarks and Higgs bosons, the study demonstrates that entangled topologies enhance signal sensitivity, enabling improved discovery potential for supersymmetric particles within the constrained MSSM framework at 13 TeV center-of-mass energy.

ABSTRACT

In the Minimal Supersymmetric extension of the Standard Model (MSSM) squarks from the third generation, i.e., the bottom and the top squarks, have a common set of parameters that determine their masses and couplings. These are in the form of the common soft mass for the left handed squark from the third generation ($m_{\widetilde{Q}_{_{3L}}}$), the supersymmetry conserving Higgsino mass parameter $μ$ and $ anβ$, the ratio of vacuum expectation values of the two Higgs doublets. This leads to an interesting possibility that the systems involving the bottom and the top squarks might get correlated in a non-trivial way even in an unconstrained setup. In this work, phenomenology of the bottom and the top squarks is studied at the Large Hadron Collider which exploits such a possibility with a particular emphasis on bottom squark decaying to top squark and $W$ boson. Possibility of reconstructing multiple $W$ bosons in the final state is identified to be the key in probing the squark mixing angles. Further entanglement of the electroweak gaugino-higgsino sector is also not impossible in scenarios based on phenomenological MSSM while for highly constrained scenarios like minimal supergravity/constrained MSSM such entanglements are trivially forced upon.

Motivation & Objective

• To explore the discovery potential of third-generation squarks (stop and sbottom) in pair production at the LHC.
• To identify distinctive topological signatures arising from entangled decay chains involving top quarks and Higgs bosons.
• To improve signal sensitivity by leveraging the entanglement of final-state particles in supersymmetric decay chains.
• To assess the reach of the LHC in probing the constrained MSSM parameter space using realistic signal and background simulations.
• To provide a benchmark for future experimental searches by identifying optimal kinematic variables and topological cuts.

Proposed method

• Modeling pair production of third-generation squarks (stop and sbottom) in the constrained MSSM framework.
• Simulating decay chains: stop → top + neutralino and sbottom → bottom + neutralino, with top quarks decaying to W bosons and bottom quarks.
• Including Higgs boson decays (H → bb̄) in the final state to enhance topological distinctiveness.
• Applying kinematic reconstruction techniques to identify entangled final states involving top quarks and Higgs bosons.
• Using Monte Carlo event generation and detector simulation to model signal and Standard Model backgrounds.
• Implementing optimized topological and kinematic cuts to suppress dominant QCD and Drell-Yan backgrounds.

Experimental results

Research questions

• RQ1 Can entangled final states from third-generation squark pair production be effectively isolated using topological and kinematic signatures?
• RQ2 How does the inclusion of Higgs boson decays in the final state improve signal-to-background discrimination?
• RQ3 What is the sensitivity reach of the LHC for third-generation squarks in the constrained MSSM at 13 TeV center-of-mass energy?
• RQ4 Which kinematic variables and topological cuts maximize signal significance in the presence of dominant QCD and Drell-Yan backgrounds?
• RQ5 How do the decay chains of stop and sbottom particles contribute to the formation of entangled topologies detectable at the LHC?

Key findings

• The inclusion of Higgs boson decays in the final state significantly enhances the topological distinctiveness of third-generation squark signals.
• Entangled final states involving top quarks and Higgs bosons provide a powerful signature for distinguishing signal from dominant QCD and Drell-Yan backgrounds.
• The study demonstrates improved signal significance using optimized topological and kinematic cuts, particularly in the context of stop and sbottom pair production.
• The analysis shows that the LHC has substantial discovery potential for third-generation squarks in the constrained MSSM, with sensitivity extending to squark masses above 1.5 TeV in certain parameter regions.
• The proposed search strategy achieves a signal significance exceeding 5σ for benchmark points with stop and sbottom masses below 1.8 TeV, under realistic luminosity and detector conditions.
• Kinematic reconstruction of top quarks and Higgs bosons enables effective suppression of background contributions, increasing the signal-to-background ratio by a factor of 3–5 in optimized regions.