8,162 research outputs found

    Measurement of branching fractions and direct CP asymmetries for B→Kπ and B→ππ decays at Belle II

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    We report measurements of the branching fractions and direct CP asymmetries of the decays B0→K+π−, B+→K+π0, B+→K0π+, and B0→K0π0, and use these for testing the standard model through an isospin-based sum rule. In addition, we measure the branching fraction and direct CP asymmetry of the decay B+→π+π0 and the branching fraction of the decay B0→π+π−. The data are collected with the Belle II detector from e+e− collisions at the Υ(4S) resonance produced by the SuperKEKB asymmetric-energy collider and contain 387×106 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±0.13±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

    Weekly Icodec versus Daily Glargine U100 in Type 2 Diabetes without Previous Insulin

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    BackgroundInsulin icodec is an investigational once-weekly basal insulin analogue for diabetes management.MethodsWe conducted a 78-week randomized, open-label, treat-to-target phase 3a trial (including a 52-week main phase and a 26-week extension phase, plus a 5-week follow-up period) involving adults with type 2 diabetes (glycated hemoglobin level, 7 to 11%) who had not previously received insulin. Participants were randomly assigned in a 1:1 ratio to receive once-weekly insulin icodec or once-daily insulin glargine U100. The primary end point was the change in the glycated hemoglobin level from baseline to week 52; the confirmatory secondary end point was the percentage of time spent in the glycemic range of 70 to 180 mg per deciliter (3.9 to 10.0 mmol per liter) in weeks 48 to 52. Hypoglycemic episodes (from baseline to weeks 52 and 83) were recorded.ResultsEach group included 492 participants. Baseline characteristics were similar in the two groups. The mean reduction in the glycated hemoglobin level at 52 weeks was greater with icodec than with glargine U100 (from 8.50% to 6.93% with icodec [mean change, -1.55 percentage points] and from 8.44% to 7.12% with glargine U100 [mean change, -1.35 percentage points]); the estimated between-group difference (-0.19 percentage points; 95% confidence interval [CI], -0.36 to -0.03) confirmed the noninferiority (P<0.001) and superiority (P=0.02) of icodec. The percentage of time spent in the glycemic range of 70 to 180 mg per deciliter was significantly higher with icodec than with glargine U100 (71.9% vs. 66.9%; estimated between-group difference, 4.27 percentage points [95% CI, 1.92 to 6.62]; P<0.001), which confirmed superiority. Rates of combined clinically significant or severe hypoglycemia were 0.30 events per person-year of exposure with icodec and 0.16 events per person-year of exposure with glargine U100 at week 52 (estimated rate ratio, 1.64; 95% CI, 0.98 to 2.75) and 0.30 and 0.16 events per person-year of exposure, respectively, at week 83 (estimated rate ratio, 1.63; 95% CI, 1.02 to 2.61). No new safety signals were identified, and incidences of adverse events were similar in the two groups.ConclusionsGlycemic control was significantly better with once-weekly insulin icodec than with once-daily insulin glargine U100. (Funded by Novo Nordisk; ONWARDS 1 ClinicalTrials.gov number, .

    Measurement of the τ\tau-lepton mass with the Belle II experiment

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    We present a measurement of the τ\tau-lepton mass using a sample of about 175 million e+eτ+τe^+e^- \to \tau^+\tau^- events collected with the Belle II detector at the SuperKEKB e+ee^+e^- collider at a center-of-mass energy of 10.579GeV10.579\,\mathrm{Ge\kern -0.1em V}. This sample corresponds to an integrated luminosity of 190fb1190\,\mathrm{fb^{-1}}. We use the kinematic edge of the τ\tau pseudomass distribution in the decay τππ+πντ{\tau^-\to\pi^-\pi^+\pi^-\nu_\tau} and measure the τ\tau mass to be 1777.09±0.08±0.11MeV ⁣/c21777.09 \pm 0.08 \pm 0.11 \,\mathrm{Me\kern -0.1em V\!/c^2}, where the first uncertainty is statistical and the second systematic. This result is the most precise to date

    Search for rare decays B+Ds()+ηB^{+} \to D_{s}^{(\ast)+}\eta, Ds()+Kˉ0D_{s}^{(\ast)+}\bar{K}^{0}, D+ηD^{+}\eta, and D+K0D^{+}K^{0}

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    7 pages, 2 figuresInternational audienceWe present a study of rare decay modes B+Ds+h0B^{+} \to D_{s}^{+}h^{0}, B+Ds+h0B^{+} \to D_{s}^{\ast+}h^{0}, and B+D+h0B^{+} \to D^{+}h^{0}, where h0h^{0} denotes the neutral mesons η\eta or K0K^{0}, using a data sample of (772±10)×106(772 \pm 10 ) \times 10^{6} BBˉB\bar{B} events produced at the Υ(4S)\Upsilon(4S) resonance. The data were collected by the Belle detector operating at the asymmetric-energy KEKB collider. We observe no evidence for these decays, so we provide upper limits at the 90%\% confidence level on the branching fractions of B+Ds+h0B^{+} \to D_{s}^{+}h^{0}, Ds+h0D_{s}^{\ast+}h^{0}, and D+h0D^{+}h^{0} decay modes. Along with rare decay modes, we report improved measurements of the color-suppressed decay branching fractions B(Bˉ0D0η)\mathcal{B}(\bar{B}^{0} \to D^{0}\eta) = (26.6 ±\pm 1.2 ±\pm 2.1) ×\times 10510^{-5} and B(Bˉ0D0Kˉ0)\mathcal{B}(\bar{B}^{0} \to D^{0}\bar{K}^{0}) = (5.6 ±\pm 0.5 ±\pm 0.2) ×\times 10510^{-5}. The first and second uncertainties are statistical and systematic, respectively

    Precise measurement of the Ds+D^+_s lifetime at Belle II

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    7 pages, 4 figures, to be submitted to Physical Review LettersInternational audienceWe measure the lifetime of the Ds+D_s^+ meson using a data sample of 207 fb1^{-1} collected by the Belle II experiment running at the SuperKEKB asymmetric-energy e+ee^+ e^- collider. The lifetime is determined by fitting the decay-time distribution of a sample of 116×103116\times 10^3 Ds+ϕπ+D_s^+\rightarrow\phi\pi^+ decays. Our result is \tau^{}_{D^+_s} = (498.7\pm 1.7\,^{+1.1}_{-0.8}) fs, where the first uncertainty is statistical and the second is systematic. This result is significantly more precise than previous measurements

    First Simultaneous Determination of Inclusive and Exclusive Vub\left|V_{ub}\right|

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    The first simultaneous determination of the absolute value of the Cabibbo-Kobayashi-Maskawa matrix element VubV_{ub} using inclusive and exclusive decays is performed with the full Belle data set at the Υ(4S)\Upsilon(4S) resonance, corresponding to an integrated luminosity of 711 fb1{}^{-1}. We analyze collision events in which one BB meson is fully reconstructed in hadronic modes. This allows for the reconstruction of the hadronic XuX_u system of the semileptonic buνˉb \to u \ell \bar \nu_\ell decay. We separate exclusive BπνˉB \to \pi \, \ell\, \bar \nu_{\ell} decays from other inclusive BXuνˉB \to X_u \, \ell\, \bar \nu_{\ell} and backgrounds with a two-dimensional fit, that utilizes the number of charged pions in the XuX_u system and the four-momentum transfer q2q^2 between the BB and XuX_u system. Combining our measurement with information from lattice QCD and QCD calculations of the inclusive partial rate as well as external experimental information on the shape of the BπνˉB \to \pi \, \ell\, \bar \nu_{\ell} form factor, we determine Vubexcl.=(3.78±0.23±0.16±0.14)×103\left|V_{ub}^{\mathrm{excl.}} \right| = (3.78 \pm 0.23 \pm 0.16 \pm 0.14)\times 10^{-3} and Vubincl.=(3.88±0.20±0.31±0.09)×103\left|V_{ub}^{\mathrm{incl.}} \right| = (3.88 \pm 0.20 \pm 0.31 \pm 0.09)\times 10^{-3}, respectively, with the uncertainties being the statistical error, systematic errors, and theory errors. The ratio of Vubexcl./Vubincl.=0.97±0.12\left|V_{ub}^{\mathrm{excl.}} \right| / \left|V_{ub}^{\mathrm{incl.}} \right| = 0.97 \pm 0.12 is compatible with unity

    Outcomes of beta blocker use in advanced hepatocellular carcinoma treated with immune checkpoint inhibitors

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    Background: In patients with cirrhosis, portal hypertension increases intestinal permeability, dysbiosis, and bacterial translocation, promoting an inflammatory state that can lead to the progression of liver disease and development of hepatocellular carcinoma (HCC). We aimed to investigate whether beta blockers (BBs), which can mediate portal hypertension, conferred survival benefits in patients treated with immune checkpoint inhibitors (ICIs). Methods: We conducted a retrospective, observational study of 578 patients with unresectable HCC treated with ICI from 2017 to 2019 at 13 institutions across three continents. BB use was defined as exposure to BBs at any time during ICI therapy. The primary objective was to assess the association of BB exposure with overall survival (OS). Secondary objectives were to evaluate the association of BB use with progression-free survival (PFS) and objective response rate (ORR) according to RECIST 1.1 criteria. Results: In our study cohort, 203 (35%) patients used BBs at any point during ICI therapy. Of these, 51% were taking a nonselective BB. BB use was not significantly correlated with OS (hazard ratio [HR] 1.12, 95% CI 0.9-1.39, P = 0.298), PFS (HR 1.02, 95% CI 0.83-1.26, P = 0.844) or ORR (odds ratio [OR] 0.84, 95% CI 0.54-1.31, P = 0.451) in univariate or multivariate analyses. BB use was also not associated with incidence of adverse events (OR 1.38, 95% CI 0.96-1.97, P = 0.079). Specifically, nonselective BB use was not correlated with OS (HR 0.94, 95% CI 0.66-1.33, P = 0.721), PFS (HR 0.92, 0.66-1.29, P = 0.629), ORR (OR 1.20, 95% CI 0.58-2.49, P = 0.623), or rate of adverse events (OR 0.82, 95% CI 0.46-1.47, P = 0.510). Conclusion: In this real-world population of patients with unresectable HCC treated with immunotherapy, BB use was not associated with OS, PFS or ORR

    First measurement of the Michel parameter ξ\xi^\prime in the τμνˉμντ\tau^-\to\mu^-\bar{\nu}_\mu\nu_\tau decay at Belle

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    We report the first measurement of the Michel parameter ξ\xi^\prime in the τμνˉμντ\tau^-\to\mu^-\bar{\nu}_\mu\nu_\tau decay with a new method proposed just recently. The measurement is based on the reconstruction of the τμνˉμντ\tau^-\to\mu^-\bar{\nu}_\mu\nu_\tau events with subsequent muon decay-in-flight in the Belle central drift chamber. The analyzed data sample of 988fb1988\,\text{fb}^{-1} collected by the Belle detector corresponds to approximately 912×106912\times10^6 τ+τ\tau^+ \tau^- pairs. We measure ξ=0.22±0.94(stat)±0.42(syst)\xi^\prime=0.22\pm0.94(\text{stat})\pm0.42(\text{syst}), which is in agreement with the Standard Model prediction of ξ=1\xi^\prime=1. Statistical uncertainty dominates in this study, being a limiting factor, while systematic uncertainty is well under control. Our analysis proved the practicability of this promising method and its prospects for further precise measurement in future experiments.Comment: 6 pages, 4 figures, submitted to Phys. Rev. Let

    {Measurement of the B+/B0 production ratio in e+e- collisions at the \Upsilon{}(4S) resonance using B\textrightarrow{}J/\ensuremath{\psi}(\ensuremath{\ell}\ensuremath{\ell})K decays at Belle}

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