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Register a new userMeasurements of the $Upsilon(10860)$ and $Upsilon(11020)$ resonances via $sigma(e^+e^-rightarrowUpsilon(n{rm S})pi^+pi^-)$
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We report new measurements of the total cross sections for $e^+e^-to Upsilon(n{rm S})pi^+pi^-$ ($n$ = 1, 2, 3) and $e^+e^-to bbar b$ from a high-luminosity fine scan of the region $sqrt{s} = 10.63$-$11.05$ GeV with the Belle detector. We observe that the $Upsilon(n{rm S})pi^+pi^-$ spectra have little or no non-resonant component and extract from them the masses and widths of $Upsilon(10860)$ and $Upsilon(11020)$ and their relative phase. We find $M_{10860}=(10891.1pm3.2^{+0.6}_{-1.7})$ MeV/$c^2$ and $Gamma_{10860}=(53.7^{+7.1}_{-5.6},^{+1.3}_{-5.4})$ MeV and report first measurements $M_{11020}=(10987.5^{+6.4}_{-2.5},^{+9.0}_{-2.1})$ MeV/$c^2$, $Gamma_{11020}=(61^{+9}_{-19},^{+2}_{-20})$ MeV, and $phi_{rm 11020}-phi_{rm 10860} = (-1.0pm0.4,^{+1.4}_{-0.1})$ rad.
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Using data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider, we measure the energy dependence of the $e^+e^- to h_b(nP)pi^+pi^-$ $(n=1,2)$ cross sections from thresholds up to $11.02,$GeV. We find clear $Upsilon(10860)$ and $Upsilon(11020)$ peaks with little or no continuum contribution. We study the resonant substructure of the $Upsilon(11020) to h_b(nP)pi^+pi^-$ 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.
The $e^+e^- to pi^+ pi^- pi^0 chi_{bJ}$ ($J=0,~1,~2$) processes are studied using a 118~fb$^{-1}$ data sample collected at a center-of-mass energy of 10.867 GeV, in the $Upsilon(10860)$ energy range, with the Belle detector. The $pi^+ pi^- pi^0 chi_{b1}$, $pi^+pi^-pi^0chi_{b2}$, $omegachi_{b1}$ signals and the evidence of $omegachi_{b2}$ are observed for the first time and the cross sections are measured. No significant $pi^+pi^-pi^0chi_{b0}$ or $omegachi_{b0}$ signal is observed and 90% confidence level upper limits on the cross sections for these two processes are obtained. In the $pi^+pi^-pi^0$ invariant mass spectrum, significant non-$omega$ signals are also observed. We search for the $X(3872)$-like state with a hidden $bbar{b}$ component (named $X_b$) decaying into $omega Upsilon(1S)$; no significant signal is observed with a mass between $10.55$ and $10.65$ GeV/$c^2$.
We report the first observation of the processes $e^+e^-toUpsilon(rm 1S,2S)eta$ at $sqrt{s}=10.866$~GeV with a $10.2sigma$ and $16.5sigma$ significance respectively. The measured Born cross sections are $sigma(e^+e^- to Upsilon(2S)eta)=2.07 pm 0.21 pm 0.19$~pb, and $sigma(e^+e^- to Upsilon(rm 1S)eta)=0.42 pm 0.08 pm 0.04$~pb. We also set the upper limit on the cross section of the process $e^+e^- to Upsilon(rm 1S)eta^{prime}$ to be $sigma(e^+e^- to Upsilon(rm 1S)eta^{prime})<0.035$~pb at $90%$ CL. The results are obtained with the data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider in the energy range from $10.63$~GeV to $11.02$~GeV.
We calculate the cross sections and final state distributions for the processes e^+ e^- --> Upsilon(1S) (pi^+ pi^-, K^+ K^-, eta pi^0) near the Upsilon(5S) resonance based on the tetraquark hypothesis. This framework is used to analyse the data on the Upsilon(1S) pi^+ pi^- and Upsilon(1S) K^+ K^- final states [K.F. Chen et al. (Belle Collaboration), Phys. Rev. Lett. 100, 112001 (2008); I. Adachi et al. (Belle Collaboration), arXiv:0808.2445], yielding good fits. Dimeson invariant mass spectra in these processes are shown to be dominated by the corresponding light scalar and tensor states. The resulting correlations among the cross sections are worked out. We also predict sigma(e^+ e^- --> Upsilon(1S) K^+ K^-)/sigma(e^+ e^- --> Upsilon(1S) K^0 Kbar^0) = 1/4. These features provide crucial tests of the tetraquark framework and can be searched for in the currently available and forthcoming data from the B factories.
We study $eta_{rm c}$ production at center-of-mass energies $sqrt{s}$ from 4.18 to 4.60 GeV in $e^+e^-$ annihilation data collected with the BESIII detector operating at the BEPCII storage ring, corresponding to 7.3 fb$^{-1}$ of integrated luminosity. We measure the cross sections of the three different exclusive reactions $e^+e^-rightarrow eta_{rm c}pi^+ pi^-pi^0$, $e^+e^- rightarrow eta_{rm c}pi^+ pi^-$, and $e^+e^- rightarrow eta_{rm c}pi^0gamma$. We find significant $eta_{rm c}$ production in $e^+e^-rightarrow eta_{rm c}pi^+ pi^-pi^0$ at $sqrt{s}$ of 4.23 GeV and 4.26 GeV and observe a significant energy-dependent Born cross section that we measure to be consistent with the production via the intermediate $Y(4260)$ resonance. In addition, we perform a search for a charmonium-like $Z_{rm c}$ state close to the $Dbar{D}$ threshold that decays to $eta_{rm c}pi$, involving ground state charmonium, and observe no signal. Corresponding upper limits on the cross section of $eta_{rm c}$ and $Z_{rm c}$ production are provided, where the yields are not found to be significant.
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