Feasibility of Bc+ → tau+ nu_tau search without VELO hits at LHCb

Peña García, Lucía (2024) Feasibility of Bc+ → tau+ nu_tau search without VELO hits at LHCb. Bachelor's Thesis, Physics.

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Abstract

Lepton Flavour Universality (LFU) posits that the couplings of all charged leptons to the gauge bosons will be identical when corrected for their deferring masses. An observed deviation from LFU could signal at physics Beyond the Standard Model (BSM). At the LHCb group at the University of Groningen, the possibility of detecting de decay Bc+ -> tau+ nu_tau and measuring its branching fraction is being studied to probe LFU. However, this decay is particularly challenging to measure due to the presence of two neutrinos in the final state and the absence of a detectable Bc+ decay vertex. For that reason, this research team has developed a method of examining the Bc+ ->tau+ nu_tau decay which relies on hits left directly by Bc+ mesons in the VELO detector for analysis. While this method has been shown to be feasible, it significantly reduces the amount of data available for analysis. This thesis explores the feasibility of an alternative approach which does not rely on VELO hit data, increasing the available data, but reducing the number of observables used to separate between the signal decay and background decays. The study utilised data obtained with the lightweight simulation program RapidSim to train a Boosted Decision Tree classifier model on several observables from signal and background decays. The trained model was applied to a large dataset that emulated the experimentally expected data with respect to signal and background detection rates at the LHCb experiment.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Mulder, M.
Degree programme:	Physics
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	30 Aug 2024 12:08
Last Modified:	24 Sep 2024 13:28
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/34134

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