• Energy Research

Abstract We report the first measurement of the exclusive cross sections e+e− → $$ B\overline{B} $$ B B ¯ , e+e− → $$ B{\overline{B}}^{\ast } $$ B B ¯ ∗ , and e+e− → $$ {B}^{\ast }{\overline{B}}^{\ast } $$ B ∗ B ¯ ∗ in the energy range from 10.63 GeV to 11.02 GeV. The B mesons are fully reconstructed in a large number of hadronic final states and the three channels are identified using a beam-constrained-mass variable. The shapes of the exclusive cross sections show oscillatory behavior with several maxima and minima. The results are obtained using data collected by the Belle experiment at the KEKB asymmetric-energy e+e− collider.

Using data collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider, we measure the energy dependence of the e^{+}e^{-}→h_{b}(nP)π^{+}π^{-} (n=1, 2) cross sections from thresholds up to 11.02 GeV. We find clear ϒ(10860) and ϒ(11020) peaks with little or no continuum contribution. We study the resonant substructure of the ϒ(11020)→h_{b}(nP)π^{+}π^{-} transitions and find evidence that they proceed entirely via the intermediate isovector states Z_{b}(10610) and Z_{b}(10650). The relative fraction of these states is loosely constrained by the current data: The hypothesis that only Z_{b}(10610) is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only Z_{b}(10650) is produced is not excluded at a significant level.

AbstractUsing 34.7 pb−1 of data collected with the LHCb detector, the inclusive production of the X(3872) meson in pp collisions at $\sqrt{s}=7\mbox{~TeV}$ is observed for the first time. Candidates are selected in the X(3872)→J/ψπ+π− decay mode, and used to measure "Equation missing" where σ(pp→X(3872)+anything) is the inclusive production cross section of X(3872) mesons with rapidity in the range 2.5–4.5 and transverse momentum in the range 5–20 GeV/c. In addition the masses of both the X(3872) and ψ(2S) mesons, reconstructed in the J/ψπ+π− final state, are measured to be $$m_{X(3872)} = 3871.95 \pm0.48 \ (\mathrm{stat}) \pm0.12 \ (\mathrm {syst})\ \mathrm{MeV}/c^2 $$ and $$m_{\psi(2S)} = 3686.12\pm0.06 \ (\mathrm{stat}) \pm0.10 \ (\mathrm {syst})\ \mathrm{MeV}/c^2. $$

AbstractA branching fraction measurement of the $${{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} $$ B 0 → D s + π - decay is presented using proton–proton collision data collected with the LHCb experiment, corresponding to an integrated luminosity of $$5.0\,\text {fb} ^{-1} $$ 5.0 fb - 1 . The branching fraction is found to be $${\mathcal {B}} ({{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} ) =(19.4 \pm $$ B ( B 0 → D s + π - ) = ( 19.4 ± $$1.8\pm 1.3 \pm 1.2)\times 10^{-6}$$ 1.8 ± 1.3 ± 1.2 ) × 10 - 6 , where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the $${{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} $$ B 0 → D - π + , $${{D} ^+_{s}} {\rightarrow }{{K} ^+} {{K} ^-} {{\pi } ^+} $$ D s + → K + K - π + and $${{D} ^-} {\rightarrow }{{K} ^+} {{\pi } ^-} {{\pi } ^-} $$ D - → K + π - π - branching fractions. This is the most precise single measurement of this quantity to date. As this decay proceeds through a single amplitude involving a $$b{\rightarrow }u$$ b → u charged-current transition, the result provides information on non-factorisable strong interaction effects and the magnitude of the Cabibbo–Kobayashi–Maskawa matrix element $$V_{ub}$$ V ub . Additionally, the collision energy dependence of the hadronisation-fraction ratio $$f_s/f_d$$ f s / f d is measured through $${{\overline{B}} {}^0_{s}} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} $$ B ¯ s 0 → D s + π - and $${{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} $$ B 0 → D - π + decays.