We report expected sensitivities for the measurement of the three angles of the Unitarity Triangle in B meson decays using 50 ab-1 of electron-positron collisions recorded by the Belle II detector at the SuperKEKB collider at KEK, Japan.
Searches for lepton flavor violation in tau decays are unambiguous signatures of new physics. The branching ratios of tau leptons at the level of 10^-10 - 10^-9 can be probed with 50 ab^-1 of electron-positron annihilation data being collected by the Belle II experiment at the world's highest luminosity accelerator, the SuperKEKB, located at the High Energy Accelerator Research Organization, KEK, in Tsukuba, Japan. Searches with such expected sensitivity will either discover new physics or strongly constrain several new physics models.
We study charged lepton flavor violation associated with a light leptophilic axion-like particle (ALP), $X$, at the $B$-factory experiment Belle II. We focus on production of the ALP in the tau decays $τ\to X l$ with $l=e,μ$, followed by its decay via $X\to l^- l^+$. The ALP can be either promptly decaying or long-lived. We perform Monte-Carlo simulations, recasting a prompt search at Belle for lepton-flavor-violating $τ$ decays, and propose a displaced-vertex (DV) search. For both types of searches, we derive the Belle~II sensitivity reaches in both the product of branching fractions and the …
Belle II合作在SuperKEKB能量非对称e+ e对撞机上运行一个大幅升级的Belle探测器。Belle II将于2018年开始记录在Upperdance(4S)能量下的碰撞,目标是到2025年收集50 ab^{-1}的数据,是Belle实验的50倍。我们报告了测量与电荷宇称破坏相关的量的前景,特别强调了Cabibbo-Kobayashi-Maskawa角phi_3(γ)和与夸克混合矩阵元Vub相关的半轻子B介子衰变中的可观测量。
Evidence from the \babar, Belle and CDF experiments for the phenomenon of \dzdzb\ oscillations is reviewed. A summary is made of the current understanding of the parameters defining the mixing of mass eigenstates that give rise to the oscillations. Results of searches for CP violation induced by mixing, are given, and estimates for the precision of measurements that can be expected in future experiments are made.
The electroweak penguin B decays mediated by $b \to s \ell^+ \ell^- $ transitions are flavour-changing neutral current processes, and are thus sensitive to new physics owing to potential contributions of heavy particles in the quantum loop. Recently, LHCb has obtained interesting results, where the possible hints of lepton family universality violation (LFUV) could be seen. We report a new measurement of the LFUV observable $R_{K}$, the ratio of branching fractions of $B\to Kμ^{+}μ^{-}$ to $B\to Ke^{+}e^{-}$, based on the full data sample recorded by Belle at the $Υ(4S)$ resonance from $e^+e^-…
Dark Matter emission at Belle II and NA62 in Minimal Flavor Violation framework
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati(意大利国家核物理研究所,弗朗卡蒂国家实验室);Asia Pacific Center for Theoretical Physics(亚太理论物理中心);Department of Physics, Pohang University of Science and Technology(浦项科技大学物理系);Department of Physics, Kyushu University(九州大学物理系);CERN, European Organization for Nuclear Research(欧洲核子研究组织(CERN));LAPTh, Université Savoie Mont-Blanc et CNRS(萨瓦蒙布朗大学与法国国家科学研究中心联合理论物理实验室)
We measure the branching fraction for the Singly Cabibbo-suppressed decay $D^0\rightarrow K^0_S\,K^0_S\,π^+π^-$, and we search for $CP$ violation via a measurement of the $CP$ asymmetry $A^{}_{CP}$ and also the $T$-odd triple-product asymmetry $a_{CP}^{T}$. The later two measurements are complementary. We use 922~fb$^{-1}$ of data recorded by the Belle experiment, which ran at the KEKB asymmetric-energy $e^+ e^-$ collider. The branching fraction is measured relative to the Cabibbo-favored normalization channel $D^0\rightarrow K^0_S\,π^+π^-$. Singly Cabibbo-suppressed charm decays are expected …
我们报道了三体无粲衰变B+=>K+pi+pi-,B_0 => K_0 pi +pi-和B+=>K+K+K-的Dalitz分析结果,包括在B+=>K+pi+pi-模式中寻找直接的CP破坏.报道了一些准二体中间态的分支分数。我们还观察到在B+-=>rho(770)0 K +-通道中存在大的直接CP破坏的3.9 σ显著性证据。这是荷电介子衰变中CP破坏的第一个证据。使用Dalitz分析技术获得的结果与大数据样本的BBbar对收集的Belle探测器在KEKB非对称能量e+e-对撞机。
A rescaling of the SU(2) isospin triangles constraining $ϕ_2$ ($α$) that relies on measurements of the experimentally cleaner relative branching fractions, as opposed to those absolute, is proposed. Paving the way towards more systematically sustainable analysis, this method promises to eliminate a dominant systematic at Belle II amongst others, namely the uncertainty on the number of $B \bar B$ pairs in data. Furthermore, a $ϕ_2$ constraint in the $B \to ρρ$ system at LHCb that is more independent of Belle II input is shown to become viable even without a measurement of $C\!P$ violation in $B…
New Measurements of Time-Dependent CP-Violating Asymmetries in b --> s Transitions at Belle
我们基于在KEKB能量非对称e+e-对撞机的Belle探测器上的Upperion(4S)共振处收集的275 x 10^6个BBbar对的样本,对B 0--> phi K 0,K+ K-Ks,f0(980)Ks,eta' Ks,omega Ks,Ks pi 0和K*0 gamma(K*0 --> Ks pi 0)衰变中CP破坏参数进行了新的测量。一个中性B介子在一个特定的衰变通道中被完全重建,伴随的B介子的味道从它的衰变产物中被识别。从两个B衰变之间的适当的时间间隔的分布中的不对称性获得每个衰变模式的CP-违反参数。所有结果都是初步的。
Belle II has a broad $τ$ physics program, in particular in searches for lepton flavour and lepton number violations. Belle II profits from the relatively large $τ$-pair production rate in the low background environment of $e^+e^-$ -collisions at 10.58 GeV. Up to mid-2021 Belle II collected a sample corresponding to $214~\text{fb}^{-1}$ of data. We present a first measurement of the $τ$ mass, the prospects for the $τ$-lifetime measurement, and review the overall $τ$ lepton physics program of Belle II.