Sumitted to PubDB: 2026-05-12

Category: Phd Thesis

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Principal Authors	Latika Aggarwal
Date	2025-04-24
Belle II Number	BELLE2-PTHESIS-2026-016
Abstract	The Standard Model of elementary particle physics is the most successful theory to explain the fundamental particles and their interactions. Despite its success, the Standard Model leaves many questions unanswered, such as the fundamental characterstics of gravity, the source of neutrino masses, dark matter, dark energy, and the matter-antimatter asymmetry in the universe. The observed CP violation is insufficient to explain the universe's matter dominance, suggesting undiscovered sources of CP asymmetry. The Belle II experiment situated at the SuperKEKB accelerator, Japan aims to explore new physics in quark and lepton flavor transition by covering data ranges from 1 ab$^{-1}$ to 50 ab$^{-1}$. This large data sample enables detailed probes of new physics and cross-checks against Standard Model deviations. Flavor physics in the charm sector plays a key role in exploring the physics beyond the Standard Model. The Belle II experiment conducts a broad charm physics program that provides many opportunities to test the Standard Model predictions and search for the signatures of new physics. The higher trigger efficiency, excellent $\gamma$ and $\pi^{0}$ particle reconstruction, efficient flavor-tagging and access to a number of control samples for systematic studies are some of the advantages of studying charm physics at Belle II. \\ \par The analysis presented in this thesis ``measurements of the branching fraction $\mathcal{B}(D^{*+}_{s} \to D^{+}_{s} \pi^{0})$ with respect to $\mathcal{B}(D^{*+}_{s} \to D^{+}_{s} \gamma)$'' is important for understanding the strong interactions involving the charm quarks in Quantum Chromodynamics (QCD). These measurements can provide crucial input for the theoretical models. By comparing experimental results with the theoretical predictions, these models can be improved. Additionally, these measurements test the Standard Model predictions where any deviation from the expected results can indicate the presence of new physics beyond the Standard Model. These early and precise measurements from Belle II data also help in evaluating the Belle II detector's performance. These measurements are performed using an integrated luminosity of 424 fb$^{-1}$ of $e^{+}e^{-}$ collision data at or near the $\Upsilon(4S)$ resonance using the Belle II detector. This analysis reports the most precise result to date and found to be consistent with the previous measurements and theoretical predictions.
Institute	Panjab

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