arXiv subjects

Z. L. Hou

Publications and source records attributed to Z. L. Hou.

At least 37 records · Page 2Linked to original sources

arXiv2018

Search for $h_{c}\rightarrowπ^+π^-J/ψ$ via $ψ(3686)\rightarrow π^0π^+π^-J/ψ$

Using a data sample of $448.1\times10^6$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII, we perform search for the hadronic transition $h_c\rightarrowπ^+π^-J/ψ$ via $ψ(3686)\rightarrowπ^0h_c$. No signals of the transition are observed, and the upper limit on the product branching fraction $\mathcal{B}(ψ(3686)\rightarrowπ^0h_c)\mathcal{B}(h_c\rightarrowπ^+π^-J/ψ)$ at the 90% confidence level is determined to be $2.0\times10^{-6}$. This is the most stringent upper limit to date.

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arXiv2018

Study of the decays $D^+\rightarrowη^{(\prime)} e^+ν_{e}$

The charm semileptonic decays $D^+\toηe^+ν_{e}$ and $D^+\toη'e^+ν_{e}$ are studied with a sample of $e^+e^-$ collision data corresponding to an integrated luminosity of 2.93 fb$^{-1}$ collected at $\sqrt{s}$ = 3.773 GeV with the BESIII detector. We measure the branching fractions for $D^+\toηe^+ν_{e}$ to be $(10.74\pm0.81\pm0.51)\times10^{-4}$, and for $D^+\toη'e^+ν_{e}$ to be $(1.91\pm0.51\pm0.13)\times10^{-4}$, where the uncertainties are statistical and systematic, respectively. In addition, we perform a measurement of the form factor in the decay $D^+\toηe^+ν_{e}$. All the results are consistent with those obtained by the CLEO-c experiment.

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arXiv2018

Search for Baryon and Lepton Number Violation in $J/ψ\toΛ_c^+e^-+c.c.$

Using $1.31\times10^9$ $J/ψ$ events collected by the BESIII detector at the Beijing Electron Positron Collider, we search for the process $J/ψ\toΛ_c^+e^-+c.c.$ for the first time. In this process, both baryon and lepton number conservation is violated. No signal is found and the upper limit on the branching fraction $\mathcal{B}(J/ψ\toΛ_c^+e^-+c.c.)$ is set to be $6.9\times10^{-8}$ at the 90\% Confidence Level.

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arXiv2018

Observation of $e^{+}e^{-} \to ϕχ_{c1}$ and $ϕχ_{c2}$ at $\sqrt{s}$=4.600 GeV

Using a data sample collected with the BESIII detector operating at the BEPCII storage ring at a center-of-mass energy of $\sqrt{s}=4.600$ GeV, we search for the production of $e^{+}e^{-} \to ϕχ_{c0,1,2}$ and the charmonium-like state $Y(4140)$ in the radiative transition $e^{+}e^{-} \to γY(4140)$ with $Y(4140)$ subsequently decaying into $ϕJ/ψ$. The processes $e^{+}e^{-} \to ϕχ_{c1}$ and $ϕχ_{c2}$ are observed for the first time, each with a statistical significance of more than 10σ, and the Born cross sections are measured to be $(4.2^{+1.7}_{-1.0}\pm 0.3)$ pb and $(6.7^{+3.4}_{-1.7}\pm 0.5)$ pb, respectively, where the first uncertainties are statistical and the second systematic. No significant signals are observed for $e^{+}e^{-} \to ϕχ_{c0}$ and $e^{+}e^{-} \to γY(4140)$ and upper limits on the Born cross sections at $90\%$ confidence level are provided at $\sqrt{s}=4.600$ GeV.

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arXiv2018

Measurements of absolute branching fractions for $D$ mesons decays into two pseudoscalar mesons

Using a data sample of $e^+e^-$ collision data with an integrated luminosity of 2.93 fb$^{-1}$ taken at the center-of-mass energy $\sqrt s= 3.773$~GeV with the BESIII detector operating at the BEPCII storage rings, we measure the absolute branching fractions of the two-body hadronic decays $D^+\to π^+π^0$, $K^+ π^0$, $π^+ η$, $K^+η$, $π^+η^\prime$, $K^+η^\prime$, $K_S^0 π^+$, $K_S^0 K^+$, and $D^0\to π^+ π^-$, $K^+ K^-$, $K^\mp π^\pm$, $K_S^0 π^0$, $K_S^0 η$, $K_S^0 η^\prime$. Our results are consistent with previous measurements within uncertainties. Among them, the branching fractions for $D^+\toπ^+π^0$, $K^+π^0$, $π^+η$, $π^+η^\prime$, $K_S^0 π^+$, $K_S^0 K^+$ and $D^0 \to K_S^0 π^0$, $K_S^0 η$, $K_S^0 η^\prime$ are determined with improved precision compared to the world average values.

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arXiv2018

Observation of $e^{+}e^{-} \rightarrow K\bar{K}J/ψ$ at center-of-mass energies from 4.189 to 4.600 GeV

We investigate the process $e^{+}e^{-} \rightarrow K\bar{K}J/ψ$ at center-of-mass energies from 4.189 to 4.600 GeV using 4.7 fb$^{-1}$ of data collected by the BESIII detector at the BEPCII collider. The Born cross sections for the reactions $e^{+}e^{-} \rightarrow K^{+}K^{-}J/ψ$ and $K_{S}^{0} K_{S}^{0} J/ψ$ are measured as a function of center-of-mass energy. The energy dependence of the cross section for $e^{+}e^{-} \rightarrow K^{+}K^{-}J/ψ$ is shown to differ from that for $π^{+}π^{-}J/ψ$ in the region around the $Y(4260)$. In addition, there is evidence for a structure around 4.5 GeV in the $e^{+}e^{-} \rightarrow K^{+}K^{-}J/ψ$ cross section that is not present in $π^{+}π^{-}J/ψ$.

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arXiv2018

Measurement of the matrix elements for the decays $η^{\prime}\rightarrowηπ^+π^-$ and $η^{\prime}\rightarrowηπ^0π^0$

Based on a sample of $1.31\times10^9$ $J/ψ$ events collected with the BESIII detector, the matrix elements for the decays $η^{\prime}\toηπ^{+}π^{-}$ and $η^{\prime}\toηπ^{0}π^{0}$ are determined using 351,016 $η^{\prime}\to(η\toγγ)π^+π^-$ and 56,249 $η^{\prime}\to(η\toγγ)π^0π^0$ events with background levels less than 1\%. Two commonly used representations are used to describe the Dalitz plot density. We find that an assumption of a linear amplitude does not describe the data well. A small deviation of the obtained matrix elements between $η^{\prime}\toηπ^{+}π^{-}$ and $η^{\prime}\toηπ^{0}π^{0}$ is probably caused by the mass difference between charged and neutral pions or radiative corrections. No cusp structure in $η^{\prime}\toηπ^{0}π^{0}$ is observed.

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arXiv2017

Measurement of the absolute branching fraction of $D_{s0}^{*\pm}(2317)\to π^0 D_{s}^{\pm}$

The process $e^+ e^- \to D_{s}^{*+} D_{s0}^{*-}(2317)+c.c.$ is observed for the first time with the data sample of 567~pb$^{-1}$ collected with the BESIII detector operating at the BEPCII collider at a center-of-mass energy $\sqrt{s} = 4.6$~GeV. The statistical significance of the $D_{s0}^{*-}(2317)$ signal is $5.8σ$ and the mass is measured to be ($2318.3\pm 1.2\pm 1.2$)~MeV/$c^{2}$. The absolute branching fraction $\mathcal{B}(D_{s0}^{*-}(2317)\to π^0 D_{s}^{-})$ is measured as $1.00^{+0.00}_{-0.14}\pm 0.14$ for the first time. The uncertainties are statistical and systematic, respectively.

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arXiv2017

Dark Photon Search in the Mass Range Between 1.5 and 3.4 GeV/$c^2$

Using a data set of 2.93 fb$^{-1}$ taken at a center-of-mass energy $\sqrt{s}$ = 3.773 GeV with the BESIII detector at the BEPCII collider, we perform a search for an extra U(1) gauge boson, also denoted as a dark photon. We examine the initial state radiation reactions $e^+e^-\rightarrow e^+e^-γ_{\rm ISR}$ and $e^+e^-\rightarrow μ^+μ^-γ_{\rm ISR}$ for this search, where the dark photon would appear as an enhancement in the invariant mass distribution of the leptonic pairs. We observe no obvious enhancement in the mass range between 1.5 and 3.4 GeV/$c^{2}$ and set a 90% confidence level upper limit on the mixing strength of the dark photon and the Standard Model photon. We obtain a competitive limit in the tested mass range.

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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

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

Precise measurement of the $e^+e^-\to π^+π^-J/ψ$ cross section at center-of-mass energies from 3.77 to 4.60 GeV

The cross section for the process $e^+e^-\to π^+π^-J/ψ$ is measured precisely at center-of-mass energies from 3.77 to 4.60~GeV using 9~fb$^{-1}$ of data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of $(4222.0\pm 3.1\pm 1.4)$~MeV/$c^2$ and a width of $(44.1\pm 4.3\pm 2.0)$~MeV, while the second one has a mass of $(4320.0\pm 10.4 \pm 7.0)$~MeV/$c^2$ and a width of $(101.4^{+25.3}_{-19.7}\pm 10.2)$~MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the $Y(4260)$ resonance reported by previous experiments. The precision of its resonant parameters is improved significantly. The second resonance is observed in $e^+e^-\to π^+π^-J/ψ$ for the first time. The statistical significance of this resonance is estimated to be larger than $7.6σ$. The mass and width of the second resonance agree with the $Y(4360)$ resonance reported by the $BABAR$ and Belle experiments within errors. Finally, the $Y(4008)$ resonance previously observed by the Belle experiment is not confirmed in the description of the BESIII data.

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arXiv2016

Measurements of the absolute branching fractions for $D_{s}^{+}\rightarrowηe^{+}ν_{e}$ and $D_{s}^{+}\rightarrowη^{\prime} e^{+}ν_{e}$

By analyzing 482 pb$^{-1}$ of $e^+e^-$ collision data collected at $\sqrt s=4.009$ GeV with the BESIII detector at the BEPCII collider, we measure the absolute branching fractions for the semileptonic decays $D_{s}^{+}\toηe^{+}ν_{e}$ and $D_{s}^{+}\to η'e^{+}ν_{e}$ to be ${B}(D_{s}^{+}\rightarrowηe^{+}ν_{e})=(2.30\pm0.31\pm0.08)$\% and ${B}(D_{s}^{+}\rightarrowη'e^{+} ν_{e}) = (0.93\pm0.30\pm0.05)$\%, respectively, and their ratio $\frac{{B}(D_{s}^{+}\rightarrowη'e^{+}ν_{e})} {{B}(D_{s}^{+}\rightarrowηe^{+}ν_{e})}=0.40\pm0.14\pm0.02$, where the first uncertainties are statistical and the second ones are systematic. The results are in good agreement with previous measurements within uncertainties; they can be used to determine the $η-η'$ mixing angle and improve upon the $D_s^+$ semileptonic branching ratio precision.

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arXiv2016

Measurement of the $D_s^+ \to \ell^+ν_\ell$ branching fractions and the decay constant $f_{D_s^+}$

Using 482~pb$^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of $\sqrt{s} = 4.009$ GeV with the BESIII detector, we measure the branching fractions of the decays $D_s^+\toμ^+ν_μ$ and $D_s^+\toτ^+ν_τ$. By constraining the ratio of decay rates of $D_s^+$ to $τ^+ν_τ$ and to $μ^+ν_μ$ to the Standard Model prediction, the branching fractions are determined to be $\mathcal{B}(D_s^+ \to μ^+ν_μ) = (0.495 \pm 0.067 \pm 0.026)\%$ and $\mathcal{B}(D_s^+ \to τ^+ν_τ) = (4.83 \pm 0.65 \pm 0.26)\%$. Using these branching fractions, we obtain a value for the decay constant $f_{D_s^+}$ of $(241.0 \pm 16.3 \pm 6.5)~\text{MeV}$, where the first error is statistical and the second systematic.

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arXiv2016

Observation of $J/ψ\to γηπ^{0}$

We present the first study of the process $J/ψ\rightarrow γηπ^{0}$ using $(223.7\pm1.4)\times10^{6}$ $J/ψ$ events accumulated with the BESIII detector at the BEPCII facility. The branching fraction for $J/ψ\rightarrow γηπ^{0}$ is measured to be $\mathcal{B}(J/ψ\rightarrow γηπ^{0}) =(2.14\pm0.18(stat)\pm0.25(syst))\times10^{-5}$. With a Bayesian approach, the upper limits of the branching fractions $\mathcal{B}(J/ψ\rightarrow γa_{0}(980),a_0(980)\rightarrowηπ^0)$ and $\mathcal{B}(J/ψ\rightarrow γa_{2}(1320),a_2(1320)\rightarrowηπ^0)$ are determined to be $2.5\times10^{-6}$ and $6.6\times10^{-6}$ at the 95\% confidence level, respectively. All of these measurements are given for the first time.

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arXiv2016

Measurement of the leptonic decay width of $J/ψ$ using initial state radiation

Using a data set of 2.93 fb$^{-1}$ taken at a center-of-mass energy of $\sqrt{s}$ = 3.773 GeV with the BESIII detector at the BEPCII collider, we measure the process $e^+e^-\rightarrow J/ψγ\rightarrow μ^+μ^-γ$ and determine the product of the branching fraction and the electronic width $\mathcal B_{μμ}\cdot Γ_{ee} = (333.4 \pm 2.5_{\rm stat} \pm 4.4_{\rm sys})$~eV. Using the earlier-published BESIII result for $\mathcal B_{μμ}$ = (5.973 $\pm$ 0.007$_{\rm stat}$ $\pm$ 0.037$_{\rm sys}$)\%, we derive the $J/ψ$ electronic width $Γ_{ee}$~= (5.58 $\pm$ 0.05$_{\rm stat}$ $\pm$ 0.08$_{\rm sys}$) keV.

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