# Belle

 2018-09-1417:16 [PUBDB-2018-03515] Conference Presentation (Invited) Ferber, T. Searches for Dark Matter at Belle II DPG - Frühjahrstagung 2018, Würzburg 18, Universität WürzburgWürzburg, Universität Würzburg, Germany, 19 Mar 2018 - 23 Mar 2018 Restricted: PDF PDF (PDFA); External link: Fulltext 2018-09-1416:46 [PUBDB-2018-03513] Poster Tenchini, F. Decay Chain Reconstruction in Belle II 23rd International Conference on Computing in High Energy and Nuclear Physics, CHEP 2018, National Palace of CultureSofia, National Palace of Culture, Bulgaria, 9 Jul 2018 - 13 Jul 2018   The Belle II detector will begin its data taking phase in 2018. Featuring a state of the art vertex detector with innovative pixel sensors, it will record collisions of e+e- beams from the SuperKEKB accelerator which is slated to provide luminosities 40x higher than KEKB.This large amount of data will come at the price of an increased beam background, as well as an operating point providing a lowered Lorentz boost when compared to Belle.This leads to new challenges for analysts seeking to perform precision measurements, as increasingly precise vertex position reconstruction and background rejection power is needed to take advantage of the unprecedented statistics provided. [...] OpenAccess: PDF PDF (PDFA); 2018-09-1414:44 [PUBDB-2018-03511] Conference Presentation (Invited) Belle II Collaboration Status and prospects of Belle II at SuperKEKB QCD and High Energy Interactions, Moriond 2018, La ThuileLa Thuile, France, 17 Mar 2018 - 24 Mar 2018   The Belle II experiment at SuperKEKB accelerator has started collecting the rst data frome+e􀀀 collisions. The dataset collected this year will be used for detector studies that willbe coupled with physics analyses, such as searches for the dark photon. [...] OpenAccess: PDF; 2018-08-3012:15 [PUBDB-2018-03276] Preprint/Report et al Observation of Transverse $\Lambda/\bar{\Lambda}$ Hyperon Polarization in $e^+e^-$ Annihilation at Belle [arXiv:1808.05000; Belle Preprint 2018-17; KEK Preprint 2018-23]   We report the first observation of the spontaneous polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons transverse to the production plane in $e^+e^-$ annihilation, which is attributed to the effect arising from a polarizing fragmentation function. For inclusive $\Lambda/\bar{\Lambda}$ production, we also report results with subtracted feed-down contributions from $\Sigma^0$ and charm. [...] OpenAccess: PDF PDF (PDFA); 2018-08-3012:06 [PUBDB-2018-03275] Preprint/Report et al Observation of $B^{+} \rightarrow p\bar{\Lambda} K^+ K^-$ and $B^{+} \rightarrow \bar{p}\Lambda K^+ K^+$ [arXiv:1807.10503; Belle Preprint 2018-15; KEK Preprint 2018-21]   We report the study of $B^{+} \rightarrow p\bar{\Lambda} K^+ K^-$ and $B^{+} \rightarrow \bar{p}\Lambda K^+ K^+$ using a $772 \times 10^6$ $B\bar{B}$ pair data sample recorded on the $\Upsilon({\rm 4S})$ resonance with the Belle detector at KEKB. These include the observations of decay modes with the corresponding branching fractions $\mathcal{B}$($B^{+} \rightarrow p\bar{\Lambda} K^+ K^-$ ) $=$ $(4.22^{+0.45}_{-0.44}\pm 0.51)\times10^{-6}$, $\mathcal{B}$($B^{+} \rightarrow \bar{p}\Lambda K^+ K^+$) $=$ $(3.81^{+0.39}_{-0.37} \pm 0.45)\times 10^{-6}$, $\mathcal{B}$($\eta_c \rightarrow p \bar{\Lambda} K^-$) $=$ $(2.9^{+0.4}_{-0.3}\pm 0.4)\times10^{-3}$ and $\mathcal{B}$($B^{+} \rightarrow p\bar{\Lambda} \phi$) $=$ $(0.818 \pm 0.215 \pm 0.078)\times10^{-6}$, where $\mathcal{B}$ denotes the decay branching fraction and the intermediate resonance decays are excluded in the four-body decay measurements.. OpenAccess: PDF PDF (PDFA); 2018-08-3011:20 [PUBDB-2018-03270] Preprint/Report et al Search for the Lepton-Flavor-Violating Decay $B^{0}\to K^{\ast 0} \mu^{\pm} e^{\mp}$ [BELLE-PREPRINT-2018-11; KEK-PREPRINT-2018-17; UCHEP-18-03; arXiv:1807.03267]   We have searched for the lepton-flavor-violating decay $B^{0}\to K^{\ast 0} \mu^{\pm} e^{\mp}$ using a data sample of 711~\invfb that contains $772 \times 10^{6}$ $B\bar{B}$ pairs. The data were collected near the \Y4S resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. [...] OpenAccess: PDF PDF (PDFA); 2018-08-3011:06 [PUBDB-2018-03267] Preprint/Report et al Evidence of charged $\Xi_{c}(2930)$ and updated measurement of $B^{0} \to K^{0} \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-}$ at Belle [arXiv:1806.09182; BELLE-PREPRINT-2018-10; KEK-PREPRINT-2018-16]   We report evidence for the charged charmed-strange baryon $\Xi_{c}(2930)$ with a signal significance of 3.9$\sigma$. The charged $\Xi_{c}(2930)$ is found in its decay to $K_{S}^{0} \Lambda_{c}$ in the substructure of $B^{0} \to K^{0}_{S} \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-}$ decays. [...] OpenAccess: PDF PDF (PDFA); 2018-08-3011:00 [PUBDB-2018-03264] Preprint/Report et al Observation of $\Upsilon(2S)\to\gamma \eta_{b}(1S)$ decay [BELLE-PREPRINT-2018-14; KEK-PREPRINT-2018-20; PNNL-SA-135879; arXiv:1807.01201]   We report the observation of $\Upsilon(2S)\to\gamma\eta_{b}(1S)$ decay based on analysis of the inclusive photon spectrum of $24.7$ fb$^{-1}$ of $e^+ e^-$ collisions at the $\Upsilon(2S)$ center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We measure a branching fraction of $\mathcal{B}(\Upsilon(2S)\to\gamma\eta_{b}(1S))=(6.1^{+0.6+0.9}_{-0.7-0.5})\times 10^{-4}$, and derive an $\eta_{b}(1S)$ mass of $9394.8^{+2.7+4.5}_{-3.1-2.7}$ MeV/$c^{2}$, where the uncertainties are statistical and systematic, respectively. [...] OpenAccess: PDF PDF (PDFA); 2018-08-3010:50 [PUBDB-2018-03260] Preprint/Report et al Observation of $e^+e^-\to\pi^+\pi^-\pi^0\chi_{b1,2}(1P)$ and search for $e^+e^-\to\phi\chi_{b1,2}(1P)$ at $\sqrt{s}=$10.96---11.05 GeV [Belle preprint 2018-12, KEK Preprint 2018-18, arXiv:1806.06203]   We report searches for the processes $e^+e^-\to\pi^+\pi^-\pi^0\chi_{bJ}$ and $e^+e^-\to\phi\chi_{bJ}$ (J=1,2) in the vicinity of the $\Upsilon(11020)$ resonance using energy scan data collected by the Belle experiment at the KEKB collider. We observe $e^+e^-\to \pi^+\pi^-\pi^0\chi_{b1}$ and find evidence for $e^+e^-\to \omega\chi_{b2}$ processes for data with center-of-mass energies from 10.96 to 11.05~GeV for the first time. [...] OpenAccess: PDF PDF (PDFA); 2018-08-3010:39 [PUBDB-2018-03258] Report/Journal Article et al Observation of an Excited $Ω ^−$ Baryon [arXiv:1805.09384; BELLE-PREPRINT-2018-09; KEK-PREPRINT-2018-3] Physical review letters 121(5), 052003 (2018) [10.1103/PhysRevLett.121.052003]   Using data recorded with the Belle detector, we observe a new excited hyperon, an $Ω^{*-}$ candidate decaying into $Ξ^0 K^-$ and $Ξ^- K_{S}^0$ with a mass of $2012.4±0.7(stat)±0.6(syst) MeV/c^2$ and a width of $Γ=6.4_{-2.0}^{+2.5}(stat)±1.6(syst) MeV$. The $Ω^{*-}$ is seen primarily in $ϒ(1S),ϒ(2S)$, and $ϒ(3S)$ decays.. OpenAccess: PDF PDF (PDFA); External link: Fulltext