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Register a new userObservation of a charged charmoniumlike structure in $e^+e^- to (D^{*} bar{D}^{*})^{pm} pi^mp$ at $sqrt{s}=4.26$GeV
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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.
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We study the process e+e- to pi+pi-J/psi at a center-of-mass energy of 4.260 GeV using a 525 pb^{-1} data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross section is measured to be (62.9pm 1.9pm 3.7) pb, consistent with the production of the Y(4260). We observe a structure at around 3.9 GeV/c^2 in the pi^pm J/psi mass spectrum, which we refer to as the Z_c(3900). If interpreted as a new particle, it is unusual in that it carries an electric charge and couples to charmonium. A fit to the pi^pm J/psi invariant mass spectrum, neglecting interference, results in a mass of (3899.0pm 3.6pm 4.9) MeV/c^2 and a width of (46pm 10pm 20) MeV. Its production ratio is measured to be R=frac{sigma(e+e- to pi^pm Z_c(3900)^mp to pi+pi-J/psi))} {sigma(e+e- to pi+pi-J/psi)}=(21.5pm 3.3pm 7.5)%. In all measurements the first errors are statistical and the second are systematic.
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 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.
A neutral structure in the $Dbar{D}^{*}$ system around the $Dbar{D}^{*}$ mass threshold is observed with a statistical significance greater than 10$sigma$ in the processes $e^{+}e^{-}rightarrow D^{+}D^{*-}pi^{0}+c.c.$ and $e^{+}e^{-}rightarrow D^{0}bar{D}^{*0}pi^{0}+c.c.$ at $sqrt{s}$ = 4.226 and 4.257 GeV in the BESIII experiment. The structure is denoted as $Z_{c}(3885)^{0}$. Assuming the presence of a resonance, its pole mass and width are determined to be ($3885.7^{+4.3}_{-5.7}$(stat)$pm 8.4$(syst)) MeV/$c^{2}$ and ($35^{+11}_{-12}$(stat)$ pm 15$(syst)) MeV, respectively. The Born cross sections are measured to be $sigma(e^{+}e^{-}to Z_{c}(3885)^{0}pi^{0}, Z_{c}(3885)^{0} to Dbar{D}^{*})=(77 pm 13$(stat)$pm 17$(syst)) pb at 4.226 GeV and ($47 pm 9$(stat)$ pm 10$(syst)) pb at 4.257 GeV. The ratio of decay rates $frac{mathcal{B}({Z_{c}(3885)^{0} to D^{+}D^{*-}+c.c.})}{mathcal{B}({Z_{c}(3885)^{0} to D^{0}bar{D}^{*0}+c.c.})}$ is determined to be $0.96 pm 0.18$(stat)$pm 0.12$(syst), consistent with no isospin violation in the process $Z_{c}(3885)^{0}to Dbar{D}^*$.
Using $e^{+}e^{-}$ collision data collected with the BESIII detector at the BEPCII collider corresponding to an integrated luminosity of 5.2 $fb^{-1}$ at center-of-mass energies ($sqrt{s}$) from 4.009 to 4.600 GeV, the process $e^{+}e^{-} to pi^{0} pi^{0}psi(3686)$ is studied for the first time. The corresponding Born cross sections are measured and found to be half of those of the reaction $e^{+}e^{-} to pi^{+}pi^{-}psi(3686)$. This is consistent with the expectation from isospin symmetry. Furthermore, the Dalitz plots for $pi^{0}pi^{0}psi(3686)$ are accordant with those of $pi^{+}pi^{-}psi(3686)$ at all energy points, and a neutral analogue to the structure in $pi^pm psi(3686)$ around 4040 MeV/$c^{2}$ first observed at $sqrt{s}$=4.416 GeV is observed in the isospin neutral mode at the same energy.
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