Recently, the team from the University of Science and Technology of China (USTC) led a groundbreaking study published in Physical Review Letters (PRL), focusing on the precise measurement of the mass of the Ωc0 charmed baryon and its first-ever measurement of rare Cabibbo-suppressed two-body hadronic decays, conducted at the Large Hadron Collider beauty (LHCb) experiment in Europe.
Mass, being a fundamental property of subatomic particles, reflects their internal structure and interaction properties, serving as a crucial tool for precise tests of the Standard Model. Accurate measurements of charmed baryon masses and decays contribute significantly to understanding non-perturbative aspects of strong interactions. The Ωc0 baryon, with its relatively long lifetime and rich decay modes, presents a hot topic in theoretical studies concerning predictions of its branching fractions. Currently, various theoretical methods exist for calculating factorizable contributions (such as W-emission transitions) and non-factorizable contributions (like W-internal emission and W-exchange transitions) in Ωc0 decays. However, significant discrepancies among different theoretical models exist, especially in predicting the branching fractions of Ωc0 → Ω–π+ and Ωc0 → Ξ–π+ decays.
Utilizing high-statistics data collected by the LHCb experiment, the USTC team achieved the most precise measurement of the Ωc0 mass to date, improving the precision of the current world average by fourfold. Notably, the experimental measurement exceeds the central values of most lattice quantum chromodynamics (LQCD) calculations, aiding in better constraining LQCD computations. Furthermore, this study observed two new Cabibbo-suppressed two-body decay modes, Ωc0 → Ω–K+ and Ωc0 → Ξ–π+, and precisely measured their relative branching fractions. These results reveal the crucial role of non-factorizable contributions in decays, testing and constraining various branching fraction theoretical models, thereby providing unique and novel insights into non-perturbative effects in quantum chromodynamics (QCD). These investigations advance our understanding of interaction dynamics in the charmed energy regime, holding significant scientific importance for precise measurements of particle physics standard models and the understanding of microscopic matter structures.
This research received substantial support from the National Natural Science Foundation of China, the Ministry of Science and Technology, the Chinese Academy of Sciences, and research projects at the University of Science and Technology of China.
Related paper: https://doi.org/10.1103/PhysRevLett.132.081802
