Measurement of branching fractions and direct $CP$ asymmetries for $B \to K \pi$ and $B \to \pi \pi$ decays at Belle II

Abstract We report measurements of the branching fractions and direct $\it{CP}$ asymmetries of the decays $B^0 \to K^+ \pi^-$, $B^+ \to K^+ \pi^0$, $B^+ \to K^0 \pi^+$, and $B^0 \to K^0 \pi^0$, and use these for testing the standard model through an isospin-based sum rule. In addition, we measure the branching fraction and direct $\it{CP}$ asymmetry of the decay $B^+ \to \pi^+\pi^0$ and the branching fraction of the decay $B^0 \to \pi^+\pi^-$. The data are collected with the Belle II detector from $e^+e^-$ collisions at the $\Upsilon(4S)$ resonance produced by the SuperKEKB asymmetric-energy collider and contain $387\times 10^6$ bottom-antibottom meson pairs. Signal yields are determined in two-dimensional fits to background-discriminating variables, and range from 500 to 3900 decays, depending on the channel. We obtain $-0.03 \pm 0.13 \pm 0.04$ for the sum rule, in agreement with the standard model expectation of zero and with a precision comparable to the best existing determinations.
Tags
Working group B Hadronic
Principal authors @  Shu-Ping Lin, Justin Skorupa, Benedikt Wach
Reference Phys.Rev.D 109, 012001 (2024), DOI: 10.1103/PhysRevD.109.012001
Document BELLE2-PUB-PH-2023-022
Links arXiv:2310.06381, Inspire, PRD
Bibtex 
@article{Belle-II:2023ksq,
    author = "Adachi, I. and others",
    collaboration = "Belle-II",
    title = "{Measurement of branching fractions and direct CP asymmetries for B{\textrightarrow}K{\ensuremath{\pi}} and B{\textrightarrow}{\ensuremath{\pi}}{\ensuremath{\pi}} decays at Belle II}",
    eprint = "2310.06381",
    archivePrefix = "arXiv",
    primaryClass = "hep-ex",
    reportNumber = "Belle II Preprint 2023-003, KEK Preprint 2022-58",
    doi = "10.1103/PhysRevD.109.012001",
    journal = "Phys. Rev. D",
    volume = "109",
    number = "1",
    pages = "012001",
    year = "2024"
}