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| Format: | Preprint |
| Published: |
2025
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| Online Access: | https://arxiv.org/abs/2501.17631 |
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| _version_ | 1866915129174523904 |
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| author | Stavroulakis, Petros |
| author_facet | Stavroulakis, Petros |
| contents | We present GFlaT, a new algorithm that uses a graph-neural-network to determine the flavor of neutral B mesons produced in $\mathrm{Υ(4S)}$ decays. We evaluate its performance using $B$ decays to flavor-specific hadronic final states reconstructed in a $362$ $\mathrm{fb}^{-1}$ sample of electron-positron collisions recorded at the $\mathrm{Υ(4S)}$ resonance with the Belle II detector at the SuperKEKB collider. We achieve an effective tagging efficiency of $(37.40 \pm 0.43 \pm 0.36) \%$, where the first uncertainty is statistical and the second systematic, which is $18\%$ better than the previous Belle II algorithm. Demonstrating the algorithm, we use $B^0 \to J/ψK_\mathrm{S}^0$ decays to measure the direct and mixing-induced CP violation parameters, $C = (-0.035 \pm 0.026 \pm 0.013)$ and $S = (0.724 \pm 0.035 \pm 0.014)$, from which we obtain $β= (23.2 \pm 1.5 \pm 0.6)^{\circ}$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_17631 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Graph Neural Network Flavor Tagger and measurement of $\mathrm{sin}2β$ at Belle II Stavroulakis, Petros High Energy Physics - Experiment We present GFlaT, a new algorithm that uses a graph-neural-network to determine the flavor of neutral B mesons produced in $\mathrm{Υ(4S)}$ decays. We evaluate its performance using $B$ decays to flavor-specific hadronic final states reconstructed in a $362$ $\mathrm{fb}^{-1}$ sample of electron-positron collisions recorded at the $\mathrm{Υ(4S)}$ resonance with the Belle II detector at the SuperKEKB collider. We achieve an effective tagging efficiency of $(37.40 \pm 0.43 \pm 0.36) \%$, where the first uncertainty is statistical and the second systematic, which is $18\%$ better than the previous Belle II algorithm. Demonstrating the algorithm, we use $B^0 \to J/ψK_\mathrm{S}^0$ decays to measure the direct and mixing-induced CP violation parameters, $C = (-0.035 \pm 0.026 \pm 0.013)$ and $S = (0.724 \pm 0.035 \pm 0.014)$, from which we obtain $β= (23.2 \pm 1.5 \pm 0.6)^{\circ}$. |
| title | Graph Neural Network Flavor Tagger and measurement of $\mathrm{sin}2β$ at Belle II |
| topic | High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2501.17631 |