PoS - Proceedings of Science
Volume 449 - The European Physical Society Conference on High Energy Physics (EPS-HEP2023) - T08 Flavour Physics and CP Violation
Recent time-dependent measurements of CP violation at Belle II
O.Β Tittel* and Β On behalf of the BELLE II collaboration
Full text: pdf
Pre-published on: January 26, 2024
Published on: March 21, 2024
We report on new time-dependent 𝐢𝑃 violation measurements using the full dataset of Belle II
collected between 2019-2022 and on improved analysis software. Hadronic penguin decays, which
proceed via a 𝑏 β†’ π‘žπ‘žπ‘  transition, are loop dominated, and thus sensitive to new physics. in this
class, we measure the time-dependent 𝐢𝑃 violation parameters 𝐢𝐢𝑃 = βˆ’0.19 Β± 0.08 Β± 0.03 and
𝑆𝐢𝑃 = 0.67 Β± 0.10 Β± 0.04 in the decay 𝐡0 β†’ πœ‚β€²πΎ0
𝑆 . In 𝑏 β†’ 𝛾(𝑠, 𝑑) transitions, radiative penguin
decays, the mixing-induced 𝐢𝑃 violation is suppressed by the polarization of the photon. New
physics contributions could, however, lead to a sizable mixing-induced term. Here, we measure
𝐢𝐢𝑃 = 0.10 Β± 0.13 Β± 0.03 and 𝑆𝐢𝑃 = 0.00 Β± 0.27 Β± 0.04 in exclusive decays to 𝐡0 β†’ πΎβˆ—0𝛾 and
𝐢𝐢𝑃 = βˆ’0.06 Β± 0.25 Β± 0.07 and 𝑆𝐢𝑃 = 0.04 Β± 0.45 Β± 0.10 in inclusive 𝐡0 β†’ 𝐾0
𝑆 πœ‹0𝛾 decays
excluding a πΎβˆ—0 mass-region. These measurements require a flavor tagging algorithm. A flavor
tagger based on a graph neural network was developed at Belle II. The increased effective tagging
efficiency of πœ–π‘‘ π‘Žπ‘” = (37.40 Β± 0.43 Β± 0.34)% is validated on the channel 𝐡0 β†’ 𝐽/πœ“πΎ0
𝑆 . The
measured values are 𝐢𝐢𝑃 = βˆ’0.035 Β± 0.026 Β± 0.012 and 𝑆𝐢𝑃 = 0.724 Β± 0.035 Β± 0.014.
DOI: https://doi.org/10.22323/1.449.0345
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access
Creative Commons LicenseCopyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.