No Arabic abstract
Using a data sample of 921.9 fb$^{-1}$ collected with the Belle detector, we study the process of $e^+e^-to D^+_sD_{s1}(2536)^-+c.c.$ via initial-state radiation. We report the first observation of a vector charmoniumlike state decaying to $D^+_sD_{s1}(2536)^-+c.c.$ with a significance of 5.9$sigma$, including the systematic uncertainties. The measured mass and width are $(4625.9^{+6.2}_{-6.0}({rm stat.})pm0.4({rm syst.}))~{rm MeV}/c^{2}$ and $(49.8^{+13.9}_{-11.5}({rm stat.})pm4.0({rm syst.}))~{rm MeV}$, respectively. The product of the $e^+e^-to D^+_sD_{s1}(2536)^-+c.c.$ cross section and the branching fraction of $D_{s1}(2536)^-to{bar D}^{*0}K^-$ is measured from the $D_s bar{D}_{s1}(2536)$ threshold to 5.59~GeV.
We report the measurement of $e^+e^- to D^+_sD^*_{s2}(2573)^-+c.c.$ via initial-state radiation using a data sample of an integrated luminosity of 921.9 fb$^{-1}$ collected with the Belle detector at the $Upsilon(4S)$ and nearby. We find evidence for an enhancement with a 3.4$sigma$ significance in the invariant mass of $D^+_sD^*_{s2}(2573)^- +c.c.$ The measured mass and width are $(4619.8^{+8.9}_{-8.0}({rm stat.})pm2.3({rm syst.}))~{rm MeV}/c^{2}$ and $(47.0^{+31.3}_{-14.8}({rm stat.})pm4.6({rm syst.}))~{rm MeV}$, respectively. The mass, width, and quantum numbers of this enhancement are consistent with the charmonium-like state at 4626 MeV/$c^2$ recently reported by Belle in $e^+e^-to D^+_sD_{s1}(2536)^-+c.c.$ The product of the $e^+e^-to D^+_sD^*_{s2}(2573)^-+c.c.$ cross section and the branching fraction of $D^*_{s2}(2573)^-to{bar D}^0K^-$ is measured from $D^+_sD^*_{s2}(2573)^-$ threshold to 5.6 GeV.
The processes $e^+e^-to D_s^+ D_{s1}(2460)^- +c.c.$ and $e^+e^-to D_s^{ast +} D_{s1}(2460)^- +c.c.$ are studied for the first time using data samples collected with the BESIII detector at the BEPCII collider. The Born cross sections of $e^+e^-to D_s^+ D_{s1}(2460)^- +c.c.$ at nine center-of-mass energies between 4.467,GeV and 4.600,GeV and those of $e^+e^-to D_s^{ast +} D_{s1}(2460)^- +c.c.$ at ${sqrt s}=$ 4.590,GeV and 4.600,GeV are measured. No obvious charmonium or charmonium-like structure is seen in the measured cross sections.
We report a study of the process $e^{+} e^{-} to (D^{*} bar{D}^{*})^{0} pi^0$ using $e^+e^-$ collision data samples with integrated luminosities of $1092 rm{pb}^{-1}$ at $sqrt{s}=4.23 rm{GeV}$ and $826 rm{pb}^{-1}$ at $sqrt{s}=4.26 rm{GeV}$ collected with the BESIII detector at the BEPCII storage ring. We observe a new neutral structure near the $(D^{*} bar{D}^{*})^{0}$ mass threshold in the $pi^0$ recoil mass spectrum, which we denote as $Z_{c}(4025)^{0}$. Assuming a Breit-Wigner line shape, its pole mass and pole width are determined to be $(4025.5^{+2.0}_{-4.7}pm3.1) rm{MeV}/c^2$ and $(23.0pm 6.0pm 1.0) rm{MeV}$, respectively. The Born cross sections of $e^{+}e^{-}to Z_{c}(4025)^{0} pi^0to (D^{*} bar{D}^{*})^{0}pi^0$ are measured to be $(61.6pm8.2pm9.0) rm{pb}$ at $sqrt{s}=4.23 rm{GeV}$ and $(43.4pm8.0pm5.4) rm{pb}$ at $sqrt{s}=4.26 rm{GeV}$. The first uncertainties are statistical and the second are systematic.
We study the process $e^+e^- to (D^{*} bar{D}^{*})^{pm} pi^mp$ at a center-of-mass energy of 4.26GeV using a 827pb$^{-1}$ data sample obtained with the BESIII detector at the Beijing Electron Positron Collider. Based on a partial reconstruction technique, the Born cross section is measured to be $(137pm9pm15)$pb. We observe a structure near the $(D^{*} bar{D}^{*})^{pm}$ threshold in the $pi^mp$ recoil mass spectrum, which we denote as the $Z^{pm}_c(4025)$. The measured mass and width of the structure are $(4026.3pm2.6pm3.7)$MeV/c$^2$ and $(24.8pm5.6pm7.7)$MeV, respectively. Its production ratio $frac{sigma(e^+e^-to Z^{pm}_c(4025)pi^mp to (D^{*} bar{D}^{*})^{pm} pi^mp)}{sigma(e^+e^-to (D^{*} bar{D}^{*})^{pm} pi^mp)}$ is determined to be $0.65pm0.09pm0.06$. The first uncertainties are statistical and the second are systematic.
Using the data samples of $(1310.6pm7.2 )times 10^{6}$ $J/psi$ events and $(448.1pm2.9)times 10^{6}$ $psi(3686)$ events collected with the BESIII detector, we search for the rare decays $J/psi to D^{0} e^{+}e^{-} +c.c.$ and $psi(3686) to D^{0} e^{+}e^{-} +c.c.$. No significant signals are observed and the corresponding upper limits on the branching fractions at the $90%$ confidence level are determined to be $Br(J/psi to D^{0} e^{+}e^{-} +c.c.)< 8.5times 10^{-8}$ and $Br (psi(3686) to D^{0} e^{+}e^{-} +c.c.)<1.4times 10^{-7}$, respectively. Our limit on $Br(J/psi to D^{0} e^{+}e^{-} +c.c.)$ is more stringent by two orders of magnitude than the previous results, and the $Br(psi(3686) to D^{0} e^{+}e^{-} +c.c.)$ is measured for the first time.