arXiv subjects

Z. L. Hou

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

At least 19 recordsLinked to original sources

arXiv2021

Evidence for $Z_{c}^{\pm}$ decays into the $ρ^{\pm} η_{c}$ final state

We study $e^{+}e^{-}$ collisions with a $π^{+}π^{-}π^{0}η_{c}$ final state using data samples collected with the BESIII detector at center-of-mass energies $\sqrt{s}=4.226$, $4.258$, $4.358$, $4.416$, and $4.600$ GeV. Evidence for the decay $\zcpm\to\rhopm\etac$ is reported with a statistical significance of $3.9σ$ with various systematic uncertainties taken into account at $\sqrt{s} = 4.226$ GeV, and the Born cross section times branching fraction $σ^{B}(\EE\to \pimp\zcpm)\times \BR(\zcpm\to\rhopm\etac)$ is measured to be $(48 \pm 11 \pm 11)\,\rm{pb}$. The $\zcpm\to \rhopm\etac$ signal is not significant at the other center-of-mass energies and the corresponding upper limits are determined. In addition, no significant signal is observed in a search for $\zcppm\to ρ^{\pm}\etac$ with the same data samples. The ratios $R_{\zc}=\BR(\zcpm\to ρ^{\pm} \etac)/\BR(\zcpm\to π^{\pm} \jpsi)$ and $R_{\zcp}=\BR(\zcppm\to ρ^{\pm} \etac)/\BR(\zcppm\to π^{\pm} \hc)$ are obtained and used to discriminate between different theoretical interpretations of the $\zcpm$ and $\zcppm$.

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arXiv2019

Observation of $η_c\toωω$ in $J/ψ\toγωω$

Using a sample of $(1310.6\pm7.0)\times10^6$ $J/ψ$ events recorded with the BESIII detector at the symmetric electron positron collider BEPCII, we report the observation of the decay of the $(1^1 S_0)$ charmonium state $η_c$ into a pair of $ω$ mesons in the process $J/ψ\toγωω$. The branching fraction is measured for the first time to be $\mathcal{B}(η_c\toωω)= (2.88\pm0.10\pm0.46\pm0.68)\times10^{-3}$, where the first uncertainty is statistical, the second systematic and the third is from the uncertainty of $\mathcal{B}(J/ψ\toγη_c)$. The mass and width of the $η_c$ are determined as $M=(2985.9\pm0.7\pm2.1)\,$MeV/$c^2$ and $Γ=(33.8\pm1.6\pm4.1)\,$MeV.

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arXiv2019

Measurement of the phase between strong and electromagnetic amplitudes of $J/ψ$ decays

Using 16 energy points of $e^{+}e^{-}$ annihilation data collected in the vicinity of the $J/ψ$ resonance with the BESIII detector and with a total integrated luminosity of around 100 pb$^{-1}$, we study the relative phase between the strong and electromagnetic amplitudes of $J/ψ$ decays. The relative phase between $Jψ$ electromagnetic decay and the continuum process ($e^{+}e^{-}$ annihilation without the $J/ψ$ resonance) is confirmed to be zero by studying the cross section lineshape of $μ^{+}μ^{-}$ production. The relative phase between $J/ψ$ strong and electromagnetic decays is then measured to be $(84.9\pm3.6)^\circ$ or $(-84.7\pm3.1)^\circ$ for the $2(π^{+}π^{-})π^{0}$ final state by investigating the interference pattern between the $J/ψ$ decay and the continuum process. This is the first measurement of the relative phase between $J/ψ$ strong and electromagnetic decays into a multihadron final state using the lineshape of the production cross section. We also study the production lineshape of the multihadron final state $ηπ^{+}π^{-}$ with $η\toπ^{+}π^{-}π^{0}$, which provides additional information about the phase between the $J/ψ$ electromagnetic decay amplitude and the continuum process. Additionally, the branching fraction of $J/ψ\to 2(π^{+}π^{-})π^{0}$ is measured to be $(4.73\pm0.44)\%$ or $(4.85\pm0.45)\%$, and the branching fraction of $J/ψ\toηπ^{+}π^{-}$ is measured to be $(3.78\pm0.68)\times10^{-4}$. Both of them are consistent with the world average values. The quoted uncertainties include both statistical and systematic uncertainties, which are mainly caused by the low statistics.

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arXiv2019

Evidence of a resonant structure in the $e^+e^-\to π^+D^0D^{*-}$ cross section between 4.05 and 4.60 GeV

The cross section of the process $e^+e^-\to π^+D^0D^{*-}$ for center-of-mass energies from 4.05 to 4.60~GeV is measured precisely using data samples collected with the BESIII detector operating at the BEPCII storage ring. Two enhancements are clearly visible in the cross section around 4.23 and 4.40~GeV. Using several models to describe the dressed cross section yields stable parameters for the first enhancement, which has a mass of $4228.6 \pm 4.1 \pm 6.3 \un{MeV}/c^2$ and a width of $77.0 \pm 6.8 \pm 6.3 \un{MeV}$, where the first uncertainties are statistical and the second ones are systematic. Our resonant mass is consistent with previous observations of the $Y(4220)$ state and the theoretical prediction of a $D\bar{D}_1(2420)$ molecule. This result is the first observation of $Y(4220)$ associated with an open-charm final state. Fits with three resonance functions with additional $Y(4260)$, $Y(4320)$, $Y(4360)$, $ψ(4415)$, or a new resonance, do not show significant contributions from either of these resonances. The second enhancement is not from a single known resonance. It could contain contributions from $ψ(4415)$ and other resonances, and a detailed amplitude analysis is required to better understand this enhancement.

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arXiv2019

Study of electromagnetic Dalitz decays $χ_{cJ} \rightarrow μ^{+}μ^{-}J/ψ$

Using $4.48 \times 10^{8}$ $ψ(3686)$ events collected with the BESIII detector, we search for the decays $χ_{cJ} \rightarrow μ^{+}μ^{-}J/ψ$ through the radiative decays $ψ(3686) \rightarrow γχ_{cJ}$, where $J=0,1,2$. The decays $χ_{c1,2} \rightarrow μ^{+}μ^{-}J/ψ$ are observed, and the corresponding branching fractions are measured to be $\mathcal{B}(χ_{c1} \rightarrow μ^{+}μ^{-}J/ψ) = (2.51 \pm 0.18 \pm 0.20)\times10^{-4}$ and $\mathcal{B}(χ_{c2} \rightarrow μ^{+}μ^{-}J/ψ) = (2.33 \pm 0.18 \pm 0.29)\times10^{-4}$, where the first uncertainty is statistical and the second one systematic. No significant $χ_{c0} \rightarrow μ^{+}μ^{-}J/ψ$ decay is observed, and the upper limit on the branching fraction is determined to be $2.0\times10^{-5}$ at 90% confidence level. Also, we present a study of di-muon invariant mass dependent transition form factor for the decays $χ_{c1,2} \rightarrow μ^{+}μ^{-}J/ψ$.

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arXiv2019

Measurement of the absolute branching fractions of $Λ_{c}^{+}\toΛηπ^{+}$ and $Σ(1385)^{+}η$

We study the decays $Λ_{c}^{+}\toΛηπ^{+}$ and $Σ(1385)^{+}η$ based on $Λ_{c}^{+}\barΛ_{c}^{-}$ pairs produced in $e^+e^-$ collisions at a center-of-mass energy of $\sqrt{s}=4.6~\mbox{GeV}$, corresponding to an integrated luminosity of $567\;\mbox{pb$^{-1}$}$. The data sample was accumulated with the BESIII detector at the BEPCII collider. The branching fractions are measured to be $\mathcal{B}(Λ_{c}^{+} \to Ληπ^{+})=(1.84\pm0.21({\rm{stat.}})\pm0.15({\rm{syst.}}))\%$ and $\mathcal{B}(Λ_{c}^{+} \to Σ(1385)^{+}η)=(0.91\pm0.18({\rm{stat.}})\pm0.09({\rm{syst.}}))\%$, constituting the most precise measurements to date.

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arXiv2019

Study of the decay $D^0\rightarrow \bar{K}^0π^-e^+ν_e$

We report a study of the decay $D^0 \rightarrow \bar{K}^0π^-e^+ν_{e}$ based on a sample of $2.93~\mathrm{fb}^{-1}$ $e^+e^-$ annihilation data collected at the center-of-mass energy of 3.773~GeV with the BESIII detector at the BEPCII collider. The total branching fraction is determined to be $\mathcal{B}(D^0\rightarrow \bar{K}^0π^-e^+ν_{e})=(1.434\pm0.029({\rm stat.})\pm0.032({\rm syst.}))\%$, which is the most precise to date. According to a detailed analysis of the involved dynamics, we find this decay is dominated with the $K^{*}(892)^-$ contribution and present an improved measurement of its branching fraction to be $\mathcal{B}(D^0\rightarrow K^{*}(892)^-e^+ν_e)=(2.033\pm0.046({\rm stat.})\pm0.047({\rm syst.}))\%$. We further access their hadronic form-factor ratios for the first time as $r_{V}=V(0)/A_1(0)=1.46\pm0.07({\rm stat.})\pm0.02({\rm syst.})$ and $r_{2}=A_2(0)/A_1(0)=0.67\pm0.06({\rm stat.})\pm0.01({\rm syst.})$. In addition, we observe a significant $\bar{K}^0π^-$ $S$-wave component accounting for $(5.51\pm0.97({\rm stat.})\pm0.62({\rm syst.}))\%$ of the total decay rate.

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arXiv2019

Search for a strangeonium-like structure $Z_s$ decaying into $ϕπ$ and a measurement of the cross section $e^+e^-\rightarrowϕππ$

Using a data sample of $e^+e^-$ collision data corresponding to an integrated luminosity of 108 pb$^{-1}$ collected with the BESIII detector at a center-of-mass energy of 2.125 GeV, we study the process $e^+e^-\rightarrow ϕππ$ and search for a strangeoniumlike structure $Z_s$ decaying into $ϕπ$. No signal is observed in the $ϕπ$ mass spectrum. Upper limits on the cross sections for $Z_s$ production at the 90\% confidence level are determined. In addition, the cross sections of $e^+e^-\rightarrowϕπ^{+}π^{-}$ and $e^+e^-\rightarrowϕπ^{0}π^{0}$ at 2.125 GeV are measured to be $(436.2\pm6.4\pm30.1)$ pb and $(237.0\pm8.6\pm15.4)$ pb, respectively, where the first uncertainties are statistical and the second systematic.

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arXiv2018

Observation of $D^{0(+)}\to K^0_Sπ^{0(+)}η^\prime$ and improved measurement of $D^0\to K^-π^+η^\prime$

By analyzing $2.93\ \rm fb^{-1}$ of data taken at a center-of-mass energy of 3.773~GeV with the BESIII detector, we measure the branching fractions of the Cabibbo-favored hadronic decays $D^0\to K^-π^+η^\prime$, $D^0\to K^0_Sπ^0η^\prime$ and $D^+\to K^0_Sπ^+η^\prime$, which are determined to be $(6.43 \pm 0.15_{\rm stat.} \pm 0.31_{\rm syst.})\times 10^{-3}$, $(2.52 \pm 0.22_{\rm stat.} \pm 0.15_{\rm syst.})\times 10^{-3}$ and $(1.90 \pm 0.17_{\rm stat.} \pm 0.13_{\rm syst.})\times 10^{-3}$, respectively. The precision of the branching fraction of $D^0\to K^-π^+η^\prime$ is significantly improved, and the processes $D^0\to K^0_Sπ^0η^\prime$ and $D^+\to K^0_Sπ^+η^\prime$ are observed for the first time.

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arXiv2018

Measurements of the absolute branching fractions and $CP$ asymmetries for $D^+\rightarrow K_{S,L}^0 K^+(π^0)$

Using $e^+e^-$ collision data corresponding to an integrated luminosity of 2.93 fb$^{-1}$ taken at a center-of-mass energy of 3.773 GeV with the BESIII detector, we determine the absolute branching fractions $\mathcal{B}(D^+\rightarrow K_S^0 K^+)$ = $(3.02 \pm 0.09 \pm 0.08)\times10^{-3}$, $\mathcal{B}(D^+\rightarrow K_S^0 K^+ π^0)$ = $(5.07 \pm 0.19 \pm 0.23)\times10^{-3}$, $\mathcal{B}(D^+\rightarrow K_L^0 K^+)$ = $(3.21 \pm 0.11 \pm 0.11)\times10^{-3}$, and $\mathcal{B}(D^+\rightarrow K_L^0 K^+ π^0)$ = $(5.24 \pm 0.22 \pm 0.22)\times10^{-3}$, where the first and second uncertainties are statistical and systematic, respectively. The branching fraction \wbrksk is consistent with the world average value and the other three branching fractions are measured for the first time. We also measure the $CP$ asymmetries for the four decays and do not find a significant deviation from zero.

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arXiv2018

Measurement of the Branching Fraction For the Semi-Leptonic Decays $D^{0(+)}\to π^{-(0)}μ^+ν_μ$ and Test of Lepton Flavor Universality

Using a data sample corresponding to an integrated luminosity of $2.93\,\rm fb^{-1}$ taken at a center-of-mass energy of 3.773\,GeV with the BESIII detector operated at the BEPCII collider, we perform an analysis of the semi-leptonic decays $D^{0(+)}\to π^{-(0)}μ^+ν_μ$. The branching fractions of $D^0\to π^-μ^+ν_μ$ and $D^+\to π^0μ^+ν_μ$ are measured to be $(0.272 \pm 0.008_{\rm stat.} \pm 0.006_{\rm syst.})\%$ and $(0.350 \pm 0.011_{\rm stat.} \pm 0.010_{\rm syst.})\%$, respectively, where the former is of much improved precision compared to previous results and the latter is determined for the first time. Using these results along with previous BESIII measurements of $D^{0(+)}\to π^{-(0)}e^+ν_e$, we calculate the branching fraction ratios to be ${\mathcal R}^0\equiv {\mathcal B}_{D^{0}\to π^{-}μ^+ν_μ}/{\mathcal B}_{D^{0}\to π^{-}e^+ν_e}=0.922\pm 0.030_{\rm stat.}\pm0.022_{\rm syst.}$ and ${\mathcal R}^+\equiv {\mathcal B}_{D^{+}\to π^{0}μ^+ν_μ}/{\mathcal B}_{D^{+}\to π^{0}e^+ν_e}=0.964\pm 0.037_{\rm stat.}\pm0.026_{\rm syst.}$, which are compatible with the theoretical expectation of lepton flavor universality within $1.7σ$ and $0.5σ$, respectively. We also examine the branching fraction ratios in different four-momentum transfer square regions, and find no significant deviations from the standard model predictions.

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arXiv2018

Observation of $h_1(1380)$ in the $J/ψ\to η^{\prime} K\bar K π$ Decay

Using $1.31 \times 10^9$ $J/ψ$ events collected by the BESIII detector at the BEPCII $e^+e^-$ collider, we report the first observation of the $h_1(1380)$ in $J/ψ\to η^{\prime} h_1(1380)$ with a significance of more than ten standard deviations. The mass and width of the possible axial-vector strangeonium candidate $h_1(1380)$ are measured to be $M = (1423.2 \pm 2.1 \pm 7.3)\mevcc$ and $Γ= (90.3 \pm 9.8 \pm 17.5)\mev$. The product branching fractions, assuming no interference, are determined to be $\mathcal{B}(J/ψ\to η^{\prime}h_1(1380)) \times \mathcal{B}(h_1(1380) \to K^{*}(892)^{+} K^{-} +c.c.) = (1.51 \pm 0.09 \pm 0.21) \times 10^{-4}$ in $η^{\prime}K^+K^-π^0$ mode and $\mathcal{B}(J/ψ\to η^{\prime}h_1(1380)) \times \mathcal{B}(h_1(1380) \to K^{*}(892)\bar K +c.c.) = (2.16 \pm 0.12 \pm 0.29) \times 10^{-4}$ in $η^{\prime}K_S^0K^{\pm}π^{\mp}$ mode. The first uncertainties are statistical and the second are systematic. Isospin symmetry violation is observed in the decays $h_1(1380) \to K^{*}(892)^{+} K^{-} +c.c.$ and $h_1(1380) \to K^{*}(892)^{0}\bar K^{0} +c.c.$. Based on the measured $h_1(1380)$ mass, the mixing angle between the states $h_1(1170)$ and $h_1(1380)$ is determined to be $(35.9\pm2.6)^{\circ}$, consistent with theoretical expectations.

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arXiv2018

Measurements of $e^+e^- \to K_{S}^{0}K^{\pm}π^{\mp}π^0$ and $K_{S}^{0}K^{\pm}π^{\mp}η$ at center-of-mass energies from $3.90$ to $4.60~\mathrm{GeV}$

Using $5.2 \ \mathrm{fb}^{-1}$ $e^+ e^-$ annihilation data samples collected with the BESIII detector, we measure the cross sections of $e^+e^- \to K_S^0 K^\pm π^\mp π^0$ and $K_{S}^{0}K^{\pm}π^{\mp}η$ at center-of-mass energies from $3.90$ to $4.60$ GeV. In addition, we search for the charmonium-like resonance $Y(4260)$ decays into $K_{S}^{0}K^{\pm}π^{\mp}π^0$ and $K_{S}^{0}K^{\pm}π^{\mp}η$, and $Z_c^{0,\pm}(3900)$ decays into $K_{S}^{0}K^{\pm}π^{\mp,0}$ and $K_{S}^{0}K^{\pm}η$. Corresponding upper limits are provided since no clear signal is observed.

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arXiv2018

First measurement of $e^+ e^- \to pK^{0}_{S}\bar{n}K^{-} + c.c.$ above open charm threshold

The process $e^+e^-\rightarrow pK^{0}_{S}\bar{n}K^{-} + c.c.$ and its intermediate processes are studied for the first time, using data samples collected with the BESIII detector at BEPCII at center-of-mass energies of 3.773, 4.008, 4.226, 4.258, 4.358, 4.416, and 4.600 GeV, with a total integrated luminosity of 7.4 fb$^{-1}$. The Born cross section of $e^+e^- \to p K^{0}_S\bar{n}K^- + c.c.$ is measured at each center-of-mass energy, but no significant resonant structure in the measured cross-section line shape between 3.773 and 4.600 GeV is observed. No evident structure is detected in the $pK^-$, $nK^{0}_S$, $pK^0_{S}$, $nK^+$, $p\bar{n}$, or $K^{0}_S K^-$ invariant mass distributions except for $Λ(1520)$. The Born cross sections of $e^+e^-\rightarrowΛ(1520)\bar{n}K^{0}_{S} + c.c.$ and $e^+e^-\rightarrow Λ(1520)\bar{p}K^{+} + c.c.$ are measured, and the 90\% confidence level upper limits on the Born cross sections of $e^+e^-\rightarrowΛ(1520)\barΛ(1520)$ are determined at the seven center-of-mass energies.

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arXiv2018

Observation of $ψ(3686) \to n\bar{n}$ and improved measurement of $ψ(3686) \to p \bar{p}$

We observe the decay $ψ(3686) \to n \bar{n}$ for the first time and measure $ψ(3686) \to p \bar{p}$ with improved accuracy by using $1.07\times 10^8$ $ψ(3686)$ events collected with the BESIII detector. The measured branching fractions are $\mathcal{B}(ψ(3686) \to n \bar{n}) = (3.06 \pm 0.06 \pm 0.14)\times 10^{-4}$ and $\mathcal{B}(ψ(3686) \to p \bar{p}) = (3.05 \pm 0.02 \pm 0.12) \times 10^{-4}$. Here, the first uncertainties are statistical and the second ones systematic. With the hypothesis that the polar angular distributions of the neutron and proton in the center-of-mass system obey $1+α\cos^2θ$, we determine the $α$ parameters to be $α_{n\bar{n}} = 0.68 \pm 0.12 \pm 0.11$ and $α_{p\bar{p}} = 1.03 \pm 0.06 \pm 0.03$ for $ψ(3686)\to n\bar{n}$ and $ψ(3686)\to p\bar{p}$, respectively.

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arXiv2018

Measurements of Absolute Branching Fractions for $Λ^+_c\toΞ^0K^+$ and $Ξ(1530)^0K^+$

We report the first measurements of absolute branching fractions for the $W$-exchange-only processes $Λ^+_c\toΞ^0K^+$ and $Λ^+_c\toΞ(1530)^0K^+$ with the double-tag technique, by analyzing an $e^{+}e^{-}$ collision data sample, that corresponds to an integrated luminosity of 567 pb$^{-1}$ collected at a center-of-mass energy of 4.6 GeV by the BESIII detector. The branching fractions are measured to be $\mathcal{B}(Λ^+_c\toΞ^0K^+)=(5.90\pm0.86\pm0.39)\times10^{-3}$ and $\mathcal{B}(Λ^+_c\toΞ(1530)^0K^+)=(5.02\pm0.99\pm0.31)\times10^{-3}$, where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.

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arXiv2018

Measurement of the absolute branching fraction of the inclusive semileptonic $Λ_c^+$ decay

Using a data sample corresponding to an integrated luminosity of 567 pb$^{-1}$ collected at a center-of-mass energy of $\sqrt{s}=4.6$ GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive semileptonic $Λ_c^+$ decay with a double-tag method. We obtain $\mathcal{B}(Λ_c^+ \rightarrow X e^+ ν_e) = (3.95\pm0.34\pm0.09)\%$, where the first uncertainty is statistical and the second systematic. Using the known $Λ_c^+$ lifetime and the charge-averaged semileptonic decay width of nonstrange charmed measons ($D^0$ and $D^+$), we obtain the ratio of the inclusive semileptonic decay widths $Γ(Λ_c^+ \rightarrow X e^+ ν_e)/\barΓ(D\rightarrow X e^+ ν_e)= 1.26\pm0.12$.

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arXiv2018

Measurement of Singly Cabibbo-Suppressed Decays $D^{0}\toπ^{0}π^{0}π^{0}$, $π^{0}π^{0}η$, $π^{0}ηη$ and $ηηη$

Using a data sample of $e^+e^-$ collision data corresponding to an integrated luminosity of 2.93 $fb^{-1}$ collected with the BESIII detector at a center-of-mass energy of $\sqrt{s}= 3.773~GeV$,we search for the singly Cabibbo-suppressed decays $D^{0}\toπ^{0}π^{0}π^{0}$, $π^{0}π^{0}η$, $π^{0}ηη$ and $ηηη$ using the double tag method. The absolute branching fractions are measured to be $\mathcal{B}(D^{0}\toπ^{0}π^{0}π^{0}) = (2.0 \pm 0.4 \pm 0.3)\times 10^{-4}$, $\mathcal{B}(D^{0}\toπ^{0}π^{0}η) = (3.8 \pm 1.1 \pm 0.7)\times 10^{-4}$ and $\mathcal{B}(D^{0}\toπ^{0}ηη) = (7.3 \pm 1.6 \pm 1.5)\times 10^{-4}$ with the statistical significances of $4.8σ$, $3.8σ$ and $5.5σ$, respectively, where the first uncertainties are statistical and the second ones systematic. No significant signal of $D^{0}\toηηη$ is found, and the upper limit on its decay branching fraction is set to be $\mathcal{B}(D^{0}\toηηη) < 1.3 \times 10^{-4}$ at the $90\%$ confidence level.

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