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Register a new userAngular analysis of the $e^+ e^- to D^{(*) pm} D^{* mp}$ process near the open charm threshold using initial-state radiation
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We report a new measurement of the exclusive $e^+ e^- to D^{(*) pm} D^{*mp}$ cross sections as a function of the center-of-mass energy from the $D^{(*) pm} D^{* mp}$ threshold through $sqrt{s}=6.0$ GeV with initial-state radiation. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of $951$ fb$^{-1}$. The accuracy of the cross section measurement is increased by a factor of two over the first Belle study. We perform the first angular analysis of the $e^+ e^- to D^{* pm} D^{* mp}$ process and decompose this exclusive cross section into three components corresponding to the $D^*$ helicities.
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An overview is presented of a method to search for $D^0to{}e^{pm}mu^{mp}$ with LHCb data. In order to reduce combinatorial backgrounds, tagged $D^0$ candidates from the decay $D^{ast+}to{}D^0pi^+$ are used. This measurement is performed with respect to $mathcal{B}left(D^0to{}pi^+pi^-right)$, which cancels uncertainties in the luminosity and $D^{ast+}$ production cross-section. It is estimated that using $3,mathrm{fb}^{-1}$ of LHCb data an upper limit can be attained of $mathcal{O}left(10^{-7}right)$ at a $90%$ confidence level.
We present a study of the process $e^+e^-topi^{pm}(Dbar{D}^*)^{mp}$ using data samples of 1092~pb$^{-1}$ at $sqrt{s}=4.23$~GeV and 826~pb$^{-1}$ at $sqrt{s}=4.26$~GeV collected with the BESIII detector at the BEPCII storage ring. With full reconstruction of the $D$ meson pair and the bachelor $pi^{pm}$ in the final state, we confirm the existence of the charged structure $Z_c(3885)^{mp}$ in the $(Dbar{D}^*)^{mp}$ system in the two isospin processes $e^+e^-topi^+D^0D^{*-}$ and $e^+e^-topi^+D^-D^{*0}$. By performing a simultaneous fit, the statistical significance of $Zc(3885)^{mp}$ signal is determined to be greater than 10$sigma$, and its pole mass and width are measured to be $M_{rm{pole}}$=(3881.7$pm$1.6(stat.)$pm$1.6(syst.))~MeV/$c^2$ and $Gamma_{rm{pole}}$=(26.6$pm$2.0(stat.)$pm$2.1(syst.))~MeV, respectively. The Born cross section times the $(Dbar{D}^*)^{mp}$ branching fraction ($sigma(e^+e^-topi^{pm}Z_{c}(3885)^{mp}) times Br(Z_{c}(3885)^{mp}to(Dbar{D}^*)^{mp})$) is measured to be $(141.6pm7.9(text{stat.})pm12.3(text{syst.}))~text{pb}$ at $sqrt{s}=4.23$~GeV and $(108.4pm6.9(text{stat.})pm8.8(text{syst.}))~text{pb}$ at $sqrt{s}=4.26$~GeV. The polar angular distribution of the $pi^{pm}$-$Z_c(3885)^{mp}$ system is consistent with the expectation of a quantum number assignment of $J^P=1^+$ for $Z_c(3885)^{mp}$.
We report a measurement of the exclusive e+e- -->Lambda_c+ Lambda_c- cross section as a function of center-of-mass energy near the Lambda_c+ Lambda_c- threshold. A clear peak with a significance of 8.2 sigma is observed in the Lambda_c+ Lambda_c- invariant mass distribution just above threshold. With an assumption of a resonance origin for the observed peak, a mass and width of M=(4634^{+8}_{-7}(stat.)^{+5}_{-8}(sys.))Mev/c2 and Gamma_tot=(92^{+40}_{-24}(stat.)}^{+10}_{-21}(sys.))MeV are determined. The analysis is based on a study of events with initial-state-radiation photons in a data sample collected with the Belle detector at the Upsilon(4S) resonance and nearby continuum with an integrated luminosity of 695/fb at the KEKB asymmetric-energy e+e- collider.
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.
The Born cross section for the process $e^+ e^- to p bar p $ is measured using the initial state radiation technique with an undetected photon. This analysis is based on datasets corresponding to an integrated luminosity of 7.5 fb$^{-1}$, collected with the BESIII detector at the BEPCII collider at center of mass energies between 3.773 and 4.600 GeV. The Born cross section for the process $e^+ e^- to p bar p $ and the proton effective form factor are determined in the $pbar p$ invariant mass range between 2.0 and 3.8 GeV/$c^2$ divided into 30 intervals. The proton form factor ratio ($|G_E|/|G_M|$) is measured in 3 intervals of the $pbar p$ invariant mass between 2.0 and 3.0 GeV/$c^2$.
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