We report results from a study of hadronic transitions of the \(\chi_{bJ}(nP)\) states of bottomonium at Belle. The \(P\)-wave states are reconstructed in transitions to the \(\Upsilon(1S)\) with the ...emission of an \(\omega\) meson. The transitions of the \(n=2\) triplet states provide a unique laboratory in which to study nonrelativistic quantum chromodynamics, as the kinematic threshold for production of an \(\omega\) and \(\Upsilon(1S)\) lies between the \(J=0\) and \(J=1\) states. A search for the \(\chi_{bJ}(3P)\) states is also reported.
We present preliminary results on the reconstruction of the \(B^0\to J\mskip 1mu / \psi\mskip 2mu K^0_{\scriptscriptstyle L}\) decay, where \(J\mskip 1mu / \psi\mskip 2mu\to\mu^+\mu^-\) or ...\(e^+e^-\). Using a dataset corresponding to a luminosity of \(62.8\pm0.6\mbox{fb}^{-1}\) collected by the Belle II experiment at the SuperKEKB asymmetric energy \(e^+e^-\) collider, we measure a total of \(267\pm21\) candidates with \(J\mskip 1mu / \psi\mskip 2mu\to\mu^+\mu^-\) and \(226\pm20\) with with \(J\mskip 1mu / \psi\mskip 2mu\to e^+e^-\). The quoted errors are statistical only.
We report updated measurements of branching fractions (\(\mathcal{B}\)) and CP-violating charge asymmetries (\(\mathcal{A_{\rm CP}}\)) for charmless \(B\) decays at Belle II, which operates on or ...near the \(\Upsilon\)(4S) resonance at the SuperKEKB asymmetric energy \(e^{+}e^{-}\) collider. We use samples of 2019 and 2020 data corresponding to 62.8 fb\(^{-1}\) of integrated luminosity. The samples are analysed using two-dimensional fits in \(\Delta E\) and \(M_{\it bc}\) to determine signal yields of approximately 568, 103, and 115 decays for the channels \(B^0 \to K^+\pi^-\), \(B^+ \to K_{\rm S}^0\pi^+\), and \(B^0 \to \pi^+\pi^-\), respectively. Signal yields are corrected for efficiencies determined from simulation and control data samples to obtain branching fractions and CP-violating asymmetries for flavour-specific channels. The results are compatible with known determinations and contribute important information to an early assessment of Belle II detector performance.
Using a data sample of 980~fb\(^{-1}\) collected with the Belle detector operating at the KEKB asymmetric-energy \(e^+e^-\) collider, we present evidence for the \(\Omega(2012)^-\) in the resonant ...substructure of \(\Omega_{c}^{0} \to \pi^+ (\bar{K}\Xi)^{-}\) (\((\bar{K}\Xi)^{-}\) = \(K^-\Xi^0\) + \(\bar{K}^0 \Xi^-\)) decays. The significance of the \(\Omega(2012)^-\) signal is 4.2\(\sigma\) after considering the systematic uncertainties. The ratio of the branching fraction of \(\Omega_{c}^{0} \to \pi^{+} \Omega(2012)^- \to \pi^+ (\bar{K}\Xi)^{-}\) relative to that of \(\Omega_{c}^{0} \to \pi^{+} \Omega^-\) is calculated to be 0.220 \(\pm\) 0.059(stat.) \(\pm\) 0.035(syst.). The individual ratios of the branching fractions of the two isospin modes are also determined, and found to be \({\cal B}(\Omega_{c}^0 \to \pi^+ \Omega(2012)^-) \times {\cal B}(\Omega(2012)^- \to K^-\Xi^0)/{\cal B}(\Omega_{c}^0 \to \pi^+ K^- \Xi^0)\) = (9.6 \(\pm\) 3.2(stat.) \(\pm\) 1.8(syst.))\% and \({\cal B}(\Omega_{c}^0 \to \pi^+ \Omega(2012)^-) \times {\cal B}(\Omega(2012)^- \to \bar{K}^0 \Xi^-)/{\cal B}(\Omega_{c}^0 \to \pi^+ \bar{K}^0 \Xi^-)\) = (5.5 \(\pm\) 2.8(stat.) \(\pm\) 0.7(syst.))\%.
We present the first measurement of the time-integrated mixing probability \(\chi_d\) using Belle II data collected at a center-of-mass (CM) energy of 10.58 GeV, corresponding to the mass of the ...\(\Upsilon\)(4S) resonance, with an integrated luminosity of \(34.6 {\rm fb}^{-1}\) at the SuperKEKB \(e^+ e^-\) collider. We reconstruct pairs of B mesons both of which decay to semileptonic final states. Using a novel methodology, we measure \(\chi_d = 0.187 \pm 0.010 \text{ (stat.)} \pm 0.019 \text{ (syst.)}\), which is compatible with existing indirect and direct determinations.
This paper presents results on charged Higgs boson production, based on LEP data collected at root s = 172 GeV, that complement the previous DELPHI results obtained at centre of mass energies up to ...161 GeV. The charged Higgs bosons are assumed to be pair
This note describes the rediscovery of \(B\to\eta' K\) decays in Belle II data, both in the charged and neutral final state: \(B_0\to\eta' K_S\) and \(B^\pm\to\eta' K^\pm\). The \(\eta'\) is searched ...for in two decay modes: \(\eta'\to\eta\pi^+\pi^-\) with \(\eta\to\gamma\gamma\), and \(\eta'\to\rho\gamma\). The analysis uses data collected in 2019 and 2020 at the SuperKEKB asymmetric \(e^+e^-\) collider, with an integrated luminosity of \(62.8~fb^{-1}\), corresponding to \(68.2\) million of \(B\bar{B}\) pairs produced. The signal yield is obtained via an unbinned maximum likelihood fit to signal sensitive variables, obtaining branching ratios: $$\mathcal{B}\left(B^\pm\to\eta'K^\pm\right) = \left(63.4~^{+3.4}_{-3.3}\,(stat)\,\pm3.2\,(syst)\,\right) \times10^{-6} $$ $$\mathcal{B}\left(B_0\to\eta'K_S\right) = \left(59.9~^{+5.8}_{-5.5}\,(stat)\,\pm2.9\,(syst)\,\right) \times10^{-6} $$ which are consistent with world average.
We report measurements of branching fractions (\(\mathcal B\)) and direct \({\it CP}\)-violating asymmetries (\(\mathcal A_{\it CP}\)) for the decays \(B^+\to K^+\pi^0\) and \(B^+ \to \pi^+\pi^0\) ...reconstructed with the Belle II detector in a sample of asymmetric-energy electron-positron collisions at the \(\Upsilon(4S)\) resonance corresponding to 62.8 \(\text{fb}^{-1}\) of integrated luminosity. The results are \(\mathcal{B}(B^+ \to K^+\pi^0) = 11.9 ^{+1.1}_{-1.0} (\rm stat)\pm 1.6(\rm syst)\times 10^{-6}\), \(\mathcal{B}(B^+ \to \pi^+\pi^0) = 5.5 ^{+1.0}_{-0.9} (\rm stat)\pm 0.7(\rm syst)\times 10^{-6}\), \(\mathcal A_{\it CP}(B^+ \to K^+\pi^0) = -0.09 \pm 0.09 (\rm stat)\pm 0.03(\rm syst)\), and \(\mathcal A_{\it CP}(B^+ \to \pi^+\pi^0) = -0.04 \pm 0.17 (\rm stat)\pm 0.06(\rm syst)\). The results are consistent with previous measurements and show a detector performance comparable with early Belle performance.
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.
A search for pair production of the lightest chargino at root-s = 130.4 and 136.3 GeV has been carried out using the data sample corresponding to the 5.92 pb(-1) recorded by the DELPHI detector ...during the high energy run of LEP in the last period of 1995.
PDF