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Register a new userSearch for $Upsilon(1S,2S) to Z^{+}_{c}Z^{(prime) -}_{c}$ and $e^{+}e^{-} to Z^{+}_{c}Z^{(prime) -}_{c}$ at $sqrt{s}$ = 10.52, 10.58, and 10.867 GeV
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The first search for $Z_{c}$ pair production in $Upsilon(1S)$ and $Upsilon(2S)$ decays and in $e^{+}e^{-}$ annihilation at $sqrt{s}$ = 10.52, 10.58, and 10.867 GeV is conducted using data collected with the Belle detector at the KEKB asymmetric energy electron-positron collider. No significant signals are observed in any of the studied modes, and the 90% credibility level upper limits on their product branching fractions in $Upsilon(1S)$ and $Upsilon(2S)$ decays (${cal B}(Upsilon(1S,2S)to Z^{+}_{c}Z^{(prime) -}_{c})times{cal B}(Z^{+}_{c}topi^{+}+cbar c)$ ($cbar c=J/psi$, $chi_{c1}(1P)$, $psi(2S)$)) and the product of Born cross section and branching fraction for $e^{+}e^{-} to Z^{+}_{c}Z^{(prime) -}_{c}$ ($sigma(e^+e^- to Z^{+}_{c}Z^{(prime) -}_{c})times {cal B}(Z^{+}_{c} to pi^+ +cbar c)$) at $sqrt{s}$ = 10.52, 10.58, and 10.867 GeV are determined. Here, $Z_{c}$ refers to the $Z_{c}(3900)$ and $Z_{c}(4200)$ observed in the $pi J/psi$ final state, the $Z_{c1}(4050)$ and $Z_{c2}(4250)$ in the $pichi_{c1}(1P)$ state, and the $Z_{c}(4050)$ and $Z_{c}(4430)$ in the $pipsi(2S)$ state.
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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.
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 results of a first search for a doubly-charged $DDK$ bound state, denoted the $R^{++}$, in $Upsilon(1S)$ and $Upsilon(2S)$ inclusive decays and via direct production in $e^+e^-$ collisions at $sqrt{s}$ = 10.520, 10.580, and 10.867 GeV. The search uses data accumulated with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. No significant signals are observed in the $D^{+}D_{s}^{*+}$ invariant-mass spectra of all studied modes. The 90% credibility level upper limits on their product branching fractions in $Upsilon(1S)$ and $Upsilon(2S)$ inclusive decays (${cal B}(Upsilon(1S,2S) to R^{++} + anything) times {cal B}(R^{++} to D^{+} D_{s}^{*+})$), and the product values of Born cross section and branching fraction in $e^+e^-$ collisions ($sigma(e^+e^- to R^{++} + anything) times {cal B}(R^{++} to D^{+} D_{s}^{*+})$) at $sqrt{s}$ = 10.520, 10.580, and 10.867 GeV under different assumptions of $R^{++}$ masses varying from 4.13 to 4.17 GeV/$c^2$, and widths varying from 0 to 5 MeV are obtained.
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.
This paper presents a full simulation study of the measurement of the production cross section ($sigma_{mathrm{ZH}}$) of the Higgsstrahlung process $mathrm{e^{+}e^{-}rightarrow ZH}$ and the Higgs boson mass ($M_{mathrm{H}}$) at the International Linear Collider (ILC), using events in which a Higgs boson recoils against a Z boson decaying into a pair of muons or electrons. The analysis is carried out for three center-of-mass energies $sqrt{s}$ = 250, 350, and 500 GeV, and two beam polarizations $mathrm{e_{L}^{-}e_{R}^{+}}$ and $mathrm{e_{R}^{-}e_{L}^{+}}$, for which the polarizations of $mathrm{e^{-}}$ and $mathrm{e^{+}}$ are $left(Pmathrm{e^{-}},Pmathrm{e^{+}}right)$ =($-$80%, +30%) and (+80%, $-$30%), respectively. Assuming an integrated luminosity of 250 $mathrm{fb^{-1}}$ for each beam polarization at $sqrt{s}$ = 250 GeV, where the best lepton momentum resolution is obtainable, $sigma_{mathrm{ZH}}$ and $M_{mathrm{H}}$ can be determined with a precision of 2.5% and 37 MeV for $mathrm{e_{L}^{-}e_{R}^{+}}$ and 2.9% and 41 MeV for $mathrm{e_{R}^{-}e_{L}^{+}}$, respectively. Regarding a 20 year ILC physics program, the expected precisions for the $mathrm{HZZ}$ coupling and $M_{mathrm{H}}$ are estimated to be 0.4% and 14 MeV, respectively. The event selection is designed to optimize the precisions of $sigma_{mathrm{ZH}}$ and $M_{mathrm{H}}$ while minimizing the bias on the measured $sigma_{mathrm{ZH}}$ due to discrepancy in signal efficiencies among Higgs decay modes. For the first time, model independence has been demonstrated to a sub-percent level for the $sigma_{mathrm{ZH}}$ measurement at each of the three center-of-mass energies. The results presented show the impact of center-of-mass energy and beam polarization on the evaluated precisons and serve as a benchmark for the planning of the ILC run scenario.
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