arXiv subjects

Y. G. Gao

Publications and source records attributed to Y. G. Gao.

187 records · Page 11Linked to original sources

arXiv2017

Measurement of $e^{+}e^{-} \to π^{0}π^{0}ψ(3686)$ at $\sqrt{s}$ from 4.009 to 4.600 GeV and observation of a neutral charmoniumlike structure

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 $e^{+}e^{-} \to π^{0} π^{0}ψ(3686)$ is studied for the first time. The corresponding Born cross sections are measured and found to be half of those of the reaction $e^{+}e^{-} \to π^{+}π^{-}ψ(3686)$. This is consistent with the expectation from isospin symmetry. Furthermore, the Dalitz plots for $π^{0}π^{0}ψ(3686)$ are accordant with those of $π^{+}π^{-}ψ(3686)$ at all energy points, and a neutral analogue to the structure in $π^\pm ψ(3686)$ 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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arXiv2017

Search for the rare decays $J/ψ\to D^{0} e^{+}e^{-} +c.c.$ and $ψ(3686) \to D^{0} e^{+}e^{-} +c.c.$

Using the data samples of $(1310.6\pm7.2 )\times 10^{6}$ $J/ψ$ events and $(448.1\pm2.9)\times 10^{6}$ $ψ(3686)$ events collected with the BESIII detector, we search for the rare decays $J/ψ\to D^{0} e^{+}e^{-} +c.c.$ and $ψ(3686) \to D^{0} e^{+}e^{-} +c.c.$. No significant signals are observed and the corresponding upper limits on the branching fractions at the $90\%$ confidence level are determined to be $Br(J/ψ\to D^{0} e^{+}e^{-} +c.c.)< 8.5\times 10^{-8}$ and $Br (ψ(3686) \to D^{0} e^{+}e^{-} +c.c.)<1.4\times 10^{-7}$, respectively. Our limit on $Br(J/ψ\to D^{0} e^{+}e^{-} +c.c.)$ is more stringent by two orders of magnitude than the previous results, and the $Br(ψ(3686) \to D^{0} e^{+}e^{-} +c.c.)$ is measured for the first time.

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arXiv2017

Improved measurements of two-photon widths of the $χ_{cJ}$ states and helicity analysis for $χ_{c2}\toγγ$

Based on $448.1 \times 10^6$ $ψ(3686)$ events collected with the BESIII detector, the decays $ψ(3686)\toγχ_{cJ}, χ_{cJ} \to γγ~(J=0, 1, 2)$ are studied. The decay branching fractions of $χ_{c0,c2} \to γγ$ are measured to be $\mathcal{B}(χ_{c0}\toγγ) = (1.93 \pm 0.08 \pm 0.05 \pm 0.05)\times 10^{-4}$ and $\mathcal{B}(χ_{c2}\toγγ) = (3.10 \pm 0.09 \pm 0.07 \pm 0.11)\times 10^{-4} $, which correspond to two-photon decay widths of $Γ_{γγ}(χ_{c0}) = 2.03 \pm 0.08 \pm 0.06 \pm 0.13 ~\rm{keV}$ and $Γ_{γγ}(χ_{c2}) = 0.60 \pm 0.02 \pm 0.01 \pm 0.04 ~\rm{keV}$ with a ratio of $\mathcal{R}=Γ_{γγ}(χ_{c2})/Γ_{γγ}(χ_{c0})= 0.295 \pm 0.014 \pm 0.007 \pm 0.027$, where the uncertainties are statistical, systematic and associated with the uncertainties of $\mathcal{B}(ψ(3686)\toγχ_{c0,c2})$ and the total widths $Γ(χ_{c0,c2})$, respectively. For the forbidden decay of $χ_{c1}\toγγ$, no signal is observed, and an upper limit on the two-photon width is obtained to be $Γ_{γγ}(χ_{c1})<5.3 ~\rm{eV}$ at the 90\% confidence level. The ratio of the two-photon widths between helicity-zero and helicity-two components in the decay $χ_{c2}\toγγ$ is also measured to be $f_{0/2} = Γ^{λ=0}_{γγ}(χ_{c2})/Γ^{λ=2}_{γγ}(χ_{c2}) = (0.0 \pm 0.6 \pm 1.2)\times 10^{-2}$, where the uncertainties are statistical and systematic, respectively.

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arXiv2017

Study of $J/ψ$ and $ψ(3686)$ decays to $π^+π^-η^\prime$

Using the data samples of $1.31\times 10^9$ $J/ψ$ events and $4.48\times 10^8$ $ψ(3686)$ events collected with the BESIII detector, partial wave analyses on the decays $J/ψ$ and $ψ(3686) \to π^+π^-η^\prime$ are performed with a relativistic covariant tensor amplitude approach. The dominant contribution is found to be $J/ψ$ and $ψ(3686)$ decays to $ρη^\prime$. In the $J/ψ$ decay, the branching fraction ${\cal B}(J/ψ\to ρη^\prime)$ is determined to be $(7.90\pm0.19(\mathrm{stat})\pm0.49(\mathrm{sys}))\times 10^{-5}$. Two solutions are found in the $ψ(3686)$ decay, and the corresponding branching fraction ${\cal B}(ψ(3686)\to ρη^\prime)$ is $(1.02\pm0.11(\mathrm{stat})\pm0.24(\mathrm{sys}))\times 10^{-5}$ for the case of constructive interference, and $(5.69\pm1.28(\mathrm{stat})\pm2.36(\mathrm{sys}))\times 10^{-6}$ for destructive interference. As a consequence, the ratios of branching fractions between $ψ(3686)$ and $J/ψ$ decays to $ρη^\prime$ are calculated to be $(12.9\pm1.4(\mathrm{stat})\pm3.1(\mathrm{sys}))$\% and $(7.2\pm1.6(\mathrm{stat})\pm3.0(\mathrm{sys}))$\%, respectively. We also determine the inclusive branching fractions of $J/ψ$ and $ψ(3686)$ decays to $π^+π^-η^\prime$ to be $(1.36\pm0.02(\mathrm{stat})\pm0.08(\mathrm{sys}))\times 10^{-4}$ and $(1.51\pm0.14(\mathrm{stat})\pm 0.23(\mathrm{sys}))\times 10^{-5}$, respectively.

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arXiv2017

Measurements of the branching fractions for the semi-leptonic decays $D^+_s\toϕe^{+}ν_{e}$, $ϕμ^{+}ν_μ$, $ημ^{+}ν_μ$ and $η'μ^{+}ν_μ$

By analyzing 482 pb$^{-1}$ of $e^+e^-$ collision data collected at the center-of-mass energy $\sqrt s=4.009$ GeV with the BESIII detector, we measure the %absolute branching fractions for the semi-leptonic decays $D_{s}^{+}\to ϕe^{+}ν_{e}$, $ϕμ^{+}ν_μ$, $ημ^{+}ν_μ$ and $η'μ^{+}ν_μ$ to be ${\mathcal B}(D_{s}^{+}\toϕe^{+}ν_{e})=(2.26\pm0.45\pm0.09)$\%, ${\mathcal B}(D_{s}^{+}\toϕμ^{+}ν_μ)=(1.94\pm0.53\pm0.09)$\%, ${\mathcal B}(D_{s}^{+}\toημ^{+}ν_μ)=(2.42\pm0.46\pm0.11)$\% and ${\mathcal B}(D_{s}^{+}\toη'μ^{+} ν_μ) = (1.06\pm0.54\pm0.07)$\%, where the first and second uncertainties are statistical and systematic, respectively. The branching fractions for the three semi-muonic decays $D_s^+\toϕμ^+ν_μ, ημ^+ν_μ$ and $η' μ^+ν_μ$ are determined for the first time and that of $D^+_s\to ϕe^+ν_e$ is consistent with the world average value within uncertainties.

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arXiv2017

Branching fraction measurements of $ψ(3686) \to γχ_{cJ}$

Using a sample of 106 million $ψ(3686)$ decays, the branching fractions of $ψ(3686) \to γχ_{c0}, ψ(3686) \to γχ_{c1}$, and $ψ(3686) \to γχ_{c2}$ are measured with improved precision to be $(9.389 \pm 0.014 \pm 0.332)\,\%$, $(9.905 \pm 0.011 \pm 0.353)\,\% $, and $(9.621 \pm 0.013 \pm 0.272)\,\% $, respectively, where the first uncertainties are statistical and the second ones are systematic. The product branching fractions of $ψ(3686) \to γχ_{c1}, χ_{c1} \to γJ/ψ$ and $ψ(3686) \to γχ_{c2}, χ_{c2} \to γJ/ψ$ and the branching fractions of $χ_{c1} \to γJ/ψ$ and $χ_{c2} \to γJ/ψ$ are also presented.

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arXiv2017

Evidence for $e^{+}e^{-} \to γη_c(1S)$ at center-of-mass energies between 4.01 and 4.60 GeV

We present first evidence for the process $e^+e^-\to γη_c(1S)$ at six center-of-mass energies between 4.01 and 4.60~GeV using data collected by the BESIII experiment operating at BEPCII. These data sets correspond to a total integrated luminosity of 4.6~fb$^{-1}$. We measure the Born cross section at each energy using a combination of twelve $η_c(1S)$ decay channels. Because the significance of the signal is marginal at each energy ($\le3.0σ$), we also combine all six energies under various assumptions for the energy-dependence of the cross section. If the process is assumed to proceed via the $Y(4260)$, we measure a peak Born cross section $σ_{\mathrm{ peak}}(e^+e^-\toγη_c(1S)) = 2.11 \pm 0.49 (\mathrm{stat.}) \pm 0.36 (\mathrm{syst.})$~pb with a statistical significance of 4.2$σ$.

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