Investigation of trigger lines in view of a search for lepton-flavor violating in Λb → Λτμ decay

Martinez Damiati, Kevin (2025) Investigation of trigger lines in view of a search for lepton-flavor violating in Λb → Λτμ decay. Bachelor's Thesis, Physics.

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Abstract

This study investigates the trigger efficiency for the rare lepton-flavour violating decay Λb → Λ τ∓ μ± at the LHCb experiment, to evaluate the performance of existing trigger lines and identify areas for optimization. Simulated signal events were generated using RapidSim, alongside a background decay mode, Λb → Λ τ± τ∓, which shares the same final-state topology. A detailed analysis was performed by varying the transverse momentum (pT ) thresholds for individual particles and assessing their impact on trigger selection. The pion daughter of Λ had the most significant effect on efficiency, with cuts above 1 GeV leading to plateaued performance. The proton and muon selections were found to be less restrictive, and tightening the muon selection offered the most potential for optimization. Trigger efficiency comparisons showed that DD tracks, which bypass the VELO, achieved trigger efficiencies of 33.4 ± 0.5% and 25.2 ± 0.5% for the signal and background decays, respectively, whereas LL tracks yielded 20.7 ± 0.8% and 13.7 ± 0.8%. The former configuration sacrifices vertex precision for higher trigger acceptance. Nevertheless, the overall decay reconstruction efficiency ranged between 3.4 ± 0.1% and 6.0 ± 0.3%, highlighting a need for more inclusive trigger designs. These findings suggest that dedicated trigger lines and refined particle selection criteria, particularly for the muon and pion, could significantly enhance signal sensitivity.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Perrevoort, A.
Degree programme:	Physics
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	15 Jul 2025 09:00
Last Modified:	15 Jul 2025 09:00
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/36197

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