Experimental Study of Charmed Hadron Decays at Electron-Positron Colliders

Sumitted to PubDB: 2026-04-28

Category: Phd Thesis

Tags: Belle Run 1

Principal Authors Lin Zhu
Date 2026-04-28
Belle II Number BELLE2-PTHESIS-2026-005
Abstract Charm physics, as one of the key frontiers in particle physics research, is dedicated to exploring the fundamental properties and interaction mechanisms of particles containing charm quarks, such as charmonium, charmed baryons, and charmed mesons. The significance of this discipline stems particularly from the unique position of the charm quark mass scale ($m_{c}\sim 1.5$ GeV) at the critical transition boundary between perturbative and non-perturbative regimes in Quantum Chromodynamics (QCD). This characteristic renders charm-related processes an exceptional window for probing the applicability limits of QCD across different energy scales. Systematic studies of hadronic decay properties in charmonium states (such as $\psi(3686)$, $\chi_{cJ}~(J=0,1,2)$, or $h_{c}$) enable the establishment of validity criteria for QCD perturbative expansion, thereby refining theoretical models through the phenomenological extraction of non-perturbative parameters. On the other hand, within the Standard Model, the $CP$-violation strength provided by the Cabibbo-Kobayashi-Maskawa (CKM) matrix remains insufficient to account for the observed matter-antimatter asymmetry. Thus, searches for new sources or mechanisms of $CP$ violation constitute a central focus of contemporary particle physics. Measurements of asymmetry parameters in charm baryon decays provide crucial experimental input for understanding fundamental symmetry violations in these processes, help uncover the underlying dynamics of charm baryons, and serve as a test of theoretical predictions. The high-luminosity $e^+e^-$ collisions at BESIII and Belle~(II) facilities have enabled the copious production of quarkonia and hadrons containing heavy quarks (such as bottom and charm). This provides a unique experimental platform for the systematic investigation of charmonium hadronic decay dynamics, charm baryon weak decay mechanisms, and the validation of theoretical models. In the study of weak decays of charm baryons, this work utilizes a data sample of $1.4~\mathrm{ab}^{-1}$ collected by the Belle and Belle II detectors at the $\Upsilon(n\mathrm{S})$ ($n=1$--$5$) center-of-mass energies and nearby continuum regions to investigate charm baryon weak decays in $e^{+}e^{-} \to c\bar{c}$ processes. A blind analysis approach was employed to measure the asymmetry parameters of the decays $\Xi_c^0\to\Lambda K_{S}^{0}$ and $\Xi_c^0\to\Sigma^{+} K^{-}$, with no significant deviation observed. Furthermore, the asymmetry parameter ($\alpha$) for $\Xi_c^0\to\Xi^-\pi^{+}$ is updated to $0.641\pm 0.029 \pm 0.007$, consistent with the previous Belle measurement. These measurements provide crucial inputs for understanding the phase shift between $S$-wave and $P$-wave amplitudes in charmed baryon decays.
Institute JLU

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