33 research outputs found

    Observation of BD()KKS0{B\to D^{(*)} K^- K^{0}_S} decays using the 2019-2022 Belle II data sample

    Full text link
    We present a measurement of the branching fractions of four B0,D()+,0KKS0B^{0,-}\to D^{(*)+,0} K^- K^{0}_S decay modes. The measurement is based on data from SuperKEKB electron-positron collisions at the Υ(4S)\Upsilon(4S) resonance collected with the Belle II detector and corresponding to an integrated luminosity of 362 fb1{362~\text{fb}^{-1}}. The event yields are extracted from fits to the distributions of the difference between expected and observed BB meson energy to separate signal and background, and are efficiency-corrected as a function of the invariant mass of the KKS0K^-K_S^0 system. We find the branching fractions to be: B(BD0KKS0)=(1.89±0.16±0.10)×104, \text{B}(B^-\to D^0K^-K_S^0)=(1.89\pm 0.16\pm 0.10)\times 10^{-4}, B(B0D+KKS0)=(0.85±0.11±0.05)×104, \text{B}(\overline B{}^0\to D^+K^-K_S^0)=(0.85\pm 0.11\pm 0.05)\times 10^{-4}, B(BD0KKS0)=(1.57±0.27±0.12)×104, \text{B}(B^-\to D^{*0}K^-K_S^0)=(1.57\pm 0.27\pm 0.12)\times 10^{-4}, B(B0D+KKS0)=(0.96±0.18±0.06)×104, \text{B}(\overline B{}^0\to D^{*+}K^-K_S^0)=(0.96\pm 0.18\pm 0.06)\times 10^{-4}, where the first uncertainty is statistical and the second systematic. These results include the first observation of B0D+KKS0\overline B{}^0\to D^+K^-K_S^0, BD0KKS0B^-\to D^{*0}K^-K_S^0, and B0D+KKS0\overline B{}^0\to D^{*+}K^-K_S^0 decays and a significant improvement in the precision of B(BD0KKS0)\text{B}(B^-\to D^0K^-K_S^0) compared to previous measurements

    Measurement of the branching fraction for the decay BK(892)+B \to K^{\ast}(892)\ell^+\ell^- at Belle II

    Full text link
    We report a measurement of the branching fraction of BK(892)+B \to K^{\ast}(892)\ell^+\ell^- decays, where +=μ+μ\ell^+\ell^- = \mu^+\mu^- or e+ee^+e^-, using electron-positron collisions recorded at an energy at or near the Υ(4S)\Upsilon(4S) mass and corresponding to an integrated luminosity of 189189 fb1^{-1}. The data was collected during 2019--2021 by the Belle II experiment at the SuperKEKB e+ee^{+}e^{-} asymmetric-energy collider. We reconstruct K(892)K^{\ast}(892) candidates in the K+πK^+\pi^-, KS0π+K_{S}^{0}\pi^+, and K+π0K^+\pi^0 final states. The signal yields with statistical uncertainties are 22±622\pm 6, 18±618 \pm 6, and 38±938 \pm 9 for the decays BK(892)μ+μB \to K^{\ast}(892)\mu^+\mu^-, BK(892)e+eB \to K^{\ast}(892)e^+e^-, and BK(892)+B \to K^{\ast}(892)\ell^+\ell^-, respectively. We measure the branching fractions of these decays for the entire range of the dilepton mass, excluding the very low mass region to suppress the BK(892)γ(e+e)B \to K^{\ast}(892)\gamma(\to e^+e^-) background and regions compatible with decays of charmonium resonances, to be \begin{equation} {\cal B}(B \to K^{\ast}(892)\mu^+\mu^-) = (1.19 \pm 0.31 ^{+0.08}_{-0.07}) \times 10^{-6}, {\cal B}(B \to K^{\ast}(892)e^+e^-) = (1.42 \pm 0.48 \pm 0.09)\times 10^{-6}, {\cal B}(B \to K^{\ast}(892)\ell^+\ell^-) = (1.25 \pm 0.30 ^{+0.08}_{-0.07}) \times 10^{-6}, \end{equation} where the first and second uncertainties are statistical and systematic, respectively. These results, limited by sample size, are the first measurements of BK(892)+B \to K^{\ast}(892)\ell^+\ell^- branching fractions from the Belle II experiment

    Angular analysis of B+ρ+ρ0B^+ \to \rho^+\rho^0 decays reconstructed in 2019, 2020, and 2021 Belle II data

    Full text link
    We report on a Belle II measurement of the branching fraction (B\mathcal{B}), longitudinal polarization fraction (fLf_L), and CP asymmetry (ACP\mathcal{A}_{CP}) of B+ρ+ρ0B^+\to \rho^+\rho^0 decays. We reconstruct B+ρ+(π+π0(γγ))ρ0(π+π)B^+\to \rho^+(\to \pi^+\pi^0(\to \gamma\gamma))\rho^0(\to \pi^+\pi^-) decays in a sample of SuperKEKB electron-positron collisions collected by the Belle II experiment in 2019, 2020, and 2021 at the Υ\Upsilon(4S) resonance and corresponding to 190 fb1^{-1} of integrated luminosity. We fit the distributions of the difference between expected and observed BB candidate energy, continuum-suppression discriminant, dipion masses, and decay angles of the selected samples, to determine a signal yield of 345±31345 \pm 31 events. The signal yields are corrected for efficiencies determined from simulation and control data samples to obtain $\mathcal{B}(B^+ \to \rho^+\rho^0) = [23.2^{+\ 2.2}_{-\ 2.1} (\rm stat) \pm 2.7 (\rm syst)]\times 10^{-6},, f_L = 0.943 ^{+\ 0.035}_{-\ 0.033} (\rm stat)\pm 0.027(\rm syst),and, and \mathcal{A}_{CP}=-0.069 \pm 0.068(\rm stat) \pm 0.060 (\rm syst).Theresultsagreewithpreviousmeasurements.Thisisthefirstmeasurementof. The results agree with previous measurements. This is the first measurement of \mathcal{A}_{CP}in in B^+\to \rho^+\rho^0$ decays reported by Belle II

    Reconstruction of BρνB \to \rho \ell \nu_\ell decays identified using hadronic decays of the recoil BB meson in 2019 -- 2021 Belle II data

    Full text link
    We present results on the semileptonic decays B0ρ+νB^0 \to \rho^- \ell^+ \nu_\ell and B+ρ0+νB^+ \to \rho^0 \ell^+ \nu_\ell in a sample corresponding to 189.9/fb of Belle II data at the SuperKEKB ee+e^- e^+ collider. Signal decays are identified using full reconstruction of the recoil BB meson in hadronic final states. We determine the total branching fractions via fits to the distributions of the square of the "missing" mass in the event and the dipion mass in the signal candidate and find B(B0ρ+ν)=(4.12±0.64(stat)±1.16(syst))×104{\mathcal{B}(B^0\to\rho^-\ell^+ \nu_\ell) = (4.12 \pm 0.64(\mathrm{stat}) \pm 1.16(\mathrm{syst})) \times 10^{-4}} and B(B+ρ0+ν)=(1.77±0.23(stat)±0.36(syst))×104{\mathcal{B}({B^+\to\rho^0\ell^+\nu_\ell}) = (1.77 \pm 0.23 (\mathrm{stat}) \pm 0.36 (\mathrm{syst})) \times 10^{-4}} where the dominant systematic uncertainty comes from modeling the nonresonant B(ππ)+νB\to (\pi\pi)\ell^+\nu_\ell contribution

    Measurement of the branching fractions and CPCP asymmetries of B+π+π0B^+ \rightarrow \pi^+ \pi^0 and B+K+π0B^+ \rightarrow K^+ \pi^0 decays in 2019-2021 Belle II data

    Full text link
    We determine the branching fractions B{\mathcal{B}} and CPCP asymmetries ACP{\mathcal{A}_{{\it CP}}} of the decays B+π+π0B^+ \rightarrow \pi^+ \pi^0 and B+K+π0B^+ \rightarrow K^+ \pi^0. The results are based on a data set containing 198 million bottom-antibottom meson pairs corresponding to an integrated luminosity of 190  fb1190\;\text{fb}^{-1} recorded by the Belle II detector in energy-asymmetric electron-positron collisions at the Υ(4S)\Upsilon (4S) resonance. We measure B(B+π+π0)=(6.12±0.53±0.53)×106{\mathcal{B}(B^+ \rightarrow \pi^+ \pi^0) = (6.12 \pm 0.53 \pm 0.53)\times 10^{-6}}, B(B+K+π0)=(14.30±0.69±0.79)×106{\mathcal{B}(B^+ \rightarrow K^+ \pi^0) = (14.30 \pm 0.69 \pm 0.79)\times 10^{-6}}, ACP(B+π+π0)=0.085±0.085±0.019{\mathcal{A}_{{\it CP}}(B^+ \rightarrow \pi^+ \pi^0) = -0.085 \pm 0.085 \pm 0.019}, and ACP(B+K+π0)=0.014±0.047±0.010{\mathcal{A}_{{\it CP}}(B^+ \rightarrow K^+ \pi^0) = 0.014 \pm 0.047 \pm 0.010}, where the first uncertainties are statistical and the second are systematic. These results improve a previous Belle II measurement and agree with the world averages

    Large expert-curated database for benchmarking document similarity detection in biomedical literature search

    Get PDF
    Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe
    corecore