Asymmetries Between Matter and Antimatter Creation in Λb Decays in high q2 region

Vetter, David (2025) Asymmetries Between Matter and Antimatter Creation in Λb Decays in high q2 region. Bachelor's Thesis, Physics.

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Abstract

The decays Λ0b → Λ0 µ+ µ− and Λ¯ 0b → Λ¯ 0 µ+ µ− are analyzed using data from the LHCb experiment at CERN, focusing on the high-q2 (squared dimuon invariant mass) region (q2 > 14.3 GeV2/c4) to search for signs of CP — combined charge conjugation (C) and parity (P) symmetry — violation (CPV) through matter–antimatter asymmetry. The presence of an asymmetry beyond the expected CPV from the CKM matrix in weak interaction, would indicate physics beyond the Standard Model (BSM). The analysis was performed on proton–proton collision data from Run 2 (years 2016-2018) at √s = 13 TeV, corresponding to an integrated luminosity of approximately 6 fb−1 . The measured raw asymmetry between Λ0b and Λ¯ 0b decays was (5.31±8.33)%, corresponding to a statistical significance of 0.421σ, concluding that the result is has no statistical significance. This result is consistent with Standard Model predictions and prior studies, providing no evidence for CPV or BSM effects in this observable. To improve the sensitivity of future analyses, increased integrated luminosity is recommended to reduce statistical uncertainties. Additionally, the implementation of a boosted decision tree tailored to this decay, along with selection criteria for the lifetime of Λ0b and Λ0 baryons, could enhance background suppression.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Perrevoort, A. and Willmann, L.
Degree programme:	Physics
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	18 Jul 2025 10:21
Last Modified:	18 Jul 2025 10:21
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/36391

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