新山　雅之
   所属   京都産業大学  理学部 物理科学科
   職種   教授
発行・発表の年月 2021/04
形態種別 その他
標題 First search for direct $CP$-violating asymmetry in $B^0 \to K^0 π^0$ decays at Belle II
執筆形態 その他
著者・共著者 Belle II Collaboration,F. Abudinén,I. Adachi,R. Adak,K. Adamczyk,P. Ahlburg,J. K. Ahn,H. Aihara,N. Akopov,A. Aloisio,F. Ameli,L. Andricek,N. Anh Ky,D. M. Asner,H. Atmacan,V. Aulchenko,T. Aushev,V. Aushev,T. Aziz,V. Babu,S. Bacher,S. Baehr,S. Bahinipati,A. M. Bakich,P. Bambade,Sw. Banerjee,S. Bansal,M. Barrett,G. Batignani,J. Baudot,A. Beaulieu,J. Becker,P. K. Behera,M. Bender,J. V. Bennett,E. Bernieri,F. U. Bernlochner,M. Bertemes,E. Bertholet,M. Bessner,S. Bettarini,V. Bhardwaj,B. Bhuyan,F. Bia
概要 We report on the first measurement of the direct $CP$-violating asymmetry
($\mathcal{A}$) in the charmless decay $B^0 \to K^0\pi^0$ at Belle II and an
updated measurement of its branching fraction ($\mathcal{B}$). We use a sample
of electron-positron collisions collected in 2019 and 2020 at the
$\Upsilon(4S)$ resonance and corresponding to $62.8$ $\text{fb}^{-1}$ of
integrated luminosity. We reconstruct and select about $50$ $B^0 \to K_S^0
\pi^0$ candidates, and we measure $\mathcal{A}_{ { K^0\pi^0 } } =
-0.40_{-0.44}^{+0.46} (\text{stat}) \pm 0.04 (\text{syst})$ and
$\mathcal{B}(B^0 \to K^0 \pi^0) = [8.5_{-1.6}^{+1.7} (\text{stat}) \pm 1.2
(\text{syst})] \times 10^{-6}$. This is the first measurement of $CP$ violation
in $B^0 \to K^0\pi^0$ decays reported by Belle II. The results agree with
previous determinations and show a detector performance comparable with the
best Belle results.
PermalinkURL http://arxiv.org/abs/2104.14871v2
researchmap用URL http://arxiv.org/pdf/2104.14871v2