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Register a new userMeasurements of $e^+e^-rightarrow eta_{rm c}pi^+ pi^-pi^0$, $eta_{rm c}pi^+ pi^-$ and $eta_{rm c}pi^0gamma$ at $sqrt{s}$ from 4.18 to 4.60,GeV, and search for a $Z_{rm c}$ state close to the $Dbar{D}$ threshold decaying to $eta_{rm c}pi$ at $sqrt{s}$ = 4.23 GeV
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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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A study of $B^{0}_{s} to eta_{c} phi$ and $B^{0}_{s} to eta_{c} pi^{+}pi^{-}$ decays is performed using $pp$ collision data corresponding to an integrated luminosity of 3.0$,rm fb^{-1}$, collected with the LHCb detector in Run~1 of the LHC. The observation of the decay $B^{0}_{s} to eta_{c} phi$ is reported, where the $eta_{c}$ meson is reconstructed in the $pbar p$, $K^+K^-pi^+pi^-$, $pi^+pi^-pi^+pi^-$ and $K^+K^-K^+K^-$ decay modes and the $phi(1020)$ in the $K^+ K^-$ decay mode. The decay $B^{0}_{s} to J/psi phi$ is used as a normalisation channel. Evidence is also reported for the decay $B^{0}_{s} to eta_{c} pi^{+}pi^{-}$, where the $eta_{c}$ meson is reconstructed in the $pbar p$ decay mode, using the decay $B^{0}_{s} to J/psi pi^+ pi^-$ as a normalisation channel. The measured branching fractions are begin{eqnarray*} {mathcal B (B^{0}_{s} to eta_{c} phi)} &=& left(5.01 pm 0.53 pm 0.27 pm 0.63 right) times 10^{-4} ,, onumber {mathcal B (B^{0}_{s} to eta_{c} pi^+ pi^-)} &=& left(1.76 pm 0.59 pm 0.12 pm 0.29 right) times 10^{-4} ,, end{eqnarray*} where in each case the first uncertainty is statistical, the second systematic and the third uncertainty is due to the limited knowledge of the external branching fractions.
We search for the M1 radiative transition psi(3686) to gammaeta_{c}(2S) by reconstructing the exclusive eta_{c}(2S) to K_{S}^{0}K^{pm}pi^{mp}pi^{+}pi^{-} decay using 1.06 times 10^8 psi(3686) events collected with the BESIII detector. The signal is observed with a statistical significance of greater than 4 standard deviations. The measured mass of the eta_{c}(2S) is 3646.9 pm 1.6(stat) pm 3.6(syst) MeV/c^2, and the width is 9.9 pm 4.8(stat) pm 2.9(syst) MeV/c^2. The product branching fraction is measured to be B(psi(3686) to gammaeta_{c}(2S)) times B(eta_{c}(2S) to K_{S}^{0}K^{pm}pi^{mp}pi^{+}pi^{-}) = (7.03 pm 2.10(stat) pm 0.70(syst)) times 10^{-6}. This measurement complements a previous BESIII measurement of psi(3686) to gammaeta_{c}(2S) with eta_{c}(2S) to K_{S}^{0} K^{pm}pi^{mp} and K^{+}K^{-}pi^{0}.
Using the inclusive photon spectrum based on a data sample collected at the $J/psi$ peak with the KEDR detector at the VEPP-4M $e^+e^-$ collider, we measured the rate of the radiative decay $J/psitogammaeta_{rm c}$ as well as $eta_{rm c}$ mass and width. Taking into account an asymmetric photon lineshape we obtained $Gamma^0_{gammaeta_{rm c}}=2.98pm0.18 phantom{|}^{+0.15}_{-0.33}$ keV, $M_{eta_{rm c}} = 2983.5 pm 1.4 phantom{|}^{+1.6}_{-3.6}$ MeV/$c^2$, $Gamma_{eta_{rm c}} = 27.2 pm 3.1 phantom{|}^{+5.4}_{-2.6}$ MeV.
We present the first upper-limit measurement of the branching fractions of the isospin-violating transitions $chi_{c0,2} rightarrow pi^{0} eta_{c}$. The measurements are performed using $106times 10^{6}$ $psi(3686)$ events accumulated with the BESIII detector at the BEPCII $e^{+}e^{-}$ collider at a center-of-mass energy corresponding to the $psi(3686)$ mass. We obtained upper limits on the branching fractions at a 90% confidence level of $B(chi_{c0} rightarrow pi^{0} eta_{c}) < 1.6 times 10^{-3}$ and $B(chi_{c2} rightarrow pi^{0} eta_{c}) < 3.2 times 10^{-3}$.
This paper presents several measurements of total production cross sections and total inelastic cross sections for the following reactions: $pi^{+}$+C, $pi^{+}$+Al, $K^{+}$+C, $K^{+}$+Al at 60 GeV/c, $pi^{+}$+C and $pi^{+}$+Al at 31 GeV/c . The measurements were made using the NA61/SHINE spectrometer at the CERN SPS. Comparisons with previous measurements are given and good agreement is seen. These interaction cross sections measurements are a key ingredient for neutrino flux prediction from the reinteractions of secondary hadrons in current and future accelerator-based long-baseline neutrino experiments.
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