arXiv subjects

Y. N. Gao

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

At least 37 records · Page 2Linked to original sources

arXiv2025

Partial wave analysis of $ψ(3686)\toΛ\barΣ^0π^0+c.c.$

Based on a sample of $(2712.4\pm14.3)\times10^6\;ψ(3686)$ events collected with the BESIII detector, a partial wave analysis of the decay $ψ(3686)\toΛ\barΣ^0π^0+c.c.$ is performed to investigate $Λ^*$ and $Σ^*$ resonances in the $π^0\barΣ^0$ and $π^0Λ$ invariant mass distributions. Significant contributions are found from the $Λ(1405)$, $Λ(1520)$, $Λ(1600)$, $Λ(1670)$, $Λ(1690)$, $Λ(1800)$, $Λ(1890)$, $Λ(2325)$, $Σ(1385)$, $Σ(1660)$, $Σ(1670)$, $Σ(1750)$, and $Σ(1910)$. The masses, widths, and production branching fractions for each component are determined. In addition, the branching fraction of $ψ(3686)\toΛ\barΣ^0π^0+c.c.$ is measured to be $(1.544\pm0.013\pm0.069)\times10^{-4}$ for the first time, where the first uncertainty is statistical and the second systematic.

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arXiv2025

Search for $Λ$-$\barΛ $ oscillation in $J/ψ\rightarrowΛ\barΛ$ decay

Using $(10087\pm44)\times 10^{6}$ $J/ψ$ decays collected by the BESIII detector at the BEPCII collider, we search for baryon number violation via $Λ-\barΛ$ oscillation in the decay $J/ψ\to Λ\barΛ$. No evidence for $Λ-\barΛ$ oscillation is observed. The upper limit on the time-integrated probability of $Λ-\barΛ$ oscillation is estimated to be $1.4\times 10^{-6}$, corresponding to an oscillation parameter less than $2.1\times 10^{-18}~\mathrm{GeV}$ at $90\%$ confidence level.

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arXiv2025

Measurement of the Decay $Ξ^{0}\toΛγ$ with Entangled $Ξ^{0}\barΞ^{0}$ Pairs

In this Letter, a systematic study of the weak radiative hyperon decay $Ξ^{0}\toΛγ$ at an electron-positron collider using entangled $Ξ^{0}\barΞ^{0}$ pair events is presented. The absolute branching fraction for this decay has been measured for the first time, and is $\left(1.347 \pm 0.066_{\mathrm stat.}\pm0.054_{\mathrm syst.}\right)\times 10^{-3}$. The decay asymmetry parameter, which characterizes the effect of parity violation in the decay, is determined to be $-0.741 \pm 0.062_{\mathrm stat.}\pm 0.019_{\mathrm syst.}$. The obtained results are consistent with the world average values within the uncertainties, offering valuable insights into the underlying mechanism governing the weak radiative hyperon decays. The charge conjugation parity ($CP$) symmetries of branching fraction and decay asymmetry parameter in the decay are also studied. No statistically significant violation of charge conjugation parity symmetry is observed.

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arXiv2025

Partial wave analyses of $ψ(3686)\to p\bar{p}π^0$ and $ψ(3686)\to p\bar{p}η$

Using a sample of $(2712\pm14)\times10^6$ $ψ(3686)$ events collected with the BESIII detector, we perform partial wave analyses of the decays $ψ(3686)\to p\bar{p}π^0$ and $ψ(3686)\to p\bar{p}η$. The branching fractions of $ψ(3686)\to p\bar{p}π^0$ and $ψ(3686)\to p\bar{p}η$ are determined to be $(133.9\pm11.2\pm2.3)\times10^{-6}$ or $(183.7\pm13.7\pm3.2)\times10^{-6}$ and $(61.5\pm6.5\pm1.1)\times10^{-6}$ or $(84.4\pm6.9\pm1.4)\times10^{-6}$, respectively, where the two solutions are caused by an ambiguous phase angle between resonant and continuum processes. Several well-established $N^*$ states are observed in the $pπ^0$ and $pη$ systems, and the corresponding branching fractions are measured. The ratio of decay widths $Γ_{N(1535)\to Nη}/Γ_{N(1535)\to Nπ}$ is determined to be $0.99\pm0.05\pm0.19$.

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arXiv2025

Measurement of the Inclusive Cross Sections of Prompt $J/ψ$ and $ψ(3686)$ Production in $e^{+}e^{-}$ Annihilation from $\sqrt{s}=3.808$ to $4.951$ GeV

The inclusive cross sections of prompt $J/ψ$ and $ψ(3686)$ production are measured at center-of-mass energies from 3.808 to 4.951 GeV. The dataset used is 22 fb$^{-1}$ of $e^{+}e^{-}$ annihilation data collected with the BESIII detector operating at the BEPCII storage ring. The results obtained are in agreement with the previous BESIII measurements of exclusive $J/ψ$ and $ψ(3686)$ production. The average values obtained for the cross sections measured in the center-of-mass energy ranges from 4.527 to 4.951 GeV for $J/ψ$ and from 4.843 to 4.951 GeV for $ψ(3686)$, where the impact of known resonances is negligible, are $14.0\pm1.7\pm3.1$ pb and $15.3\pm3.0$ pb, respectively. For $J/ψ$, the first and the second uncertainties are statistical and systematic, respectively. For $ψ(3686)$, the uncertainty is total. These values are useful for testing charmonium production models.

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arXiv2025

Search for the decay $χ_{c1}(3872)\toπ^{+}π^{-}χ_{c1}$

Using a data sample corresponding to an integrated luminosity of 10.9 fb$^{-1}$ collected at center-of-mass energies from 4.16 to 4.34 GeV with the BESIII detector, we search for the decay $χ_{c1}(3872) \to π^{+}π^{-}χ_{c1}$ in the radiative production $e^{+}e^{-} \to γχ_{c1}(3872)$. No significant signal is observed, and the ratio for the branching fraction of $χ_{c1}(3872) \to π^{+}π^{-}χ_{c1}$ to $χ_{c1}(3872) \to π^{+}π^{-}J/ψ$ is measured as $\mathcal{R}\equiv\frac{\mathcal{B}[χ_{c1}(3872) \to π^{+}π^{-}χ_{c1}]}{\mathcal{B}[χ_{c1}(3872) \to π^{+}π^{-} J/ψ]}<0.18$ at 90$\%$ confidence level. The upper limit on the product of the cross section $σ[e^{+}e^{-}\toγχ_{c1}(3872)]$ and the branching fraction $\mathcal{B}[χ_{c1}(3872)\toπ^{+}π^{-}χ_{c1}]$ at each center-of-mass energy is also given. These measurements favor the non-conventional charmonium nature of the $χ_{c1}(3872)$ state.

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arXiv2025

Search for the $e^+e^- \to ϕχ_{c1}(3872)$ process at BESIII

Based on 368.5 pb$^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies 4.914 and 4.946 GeV by the BESIII detector, the $e^+e^- \to ϕχ_{c1}(3872)$ process is searched for the first time. No significant signal is observed and the upper limits at the 90\% confidence level on the product of the Born cross section $σ(e^+e^- \to ϕχ_{c1}(3872))$ and the branching fraction $\mathcal{B}[χ_{c1}(3872)\toπ^+π^- J/ψ]$ at 4.914 and 4.946 GeV are set to be 0.85 and 0.96 pb, respectively. These measurements provide useful information for the production of the $χ_{c1}(3872)$ at $e^+e^-$ collider and deepen our understanding about the nature of this particle.

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arXiv2025

Partial Wave Analysis of $J/ψ\rightarrow γγϕ$

Using a sample of $(10087\pm44)\times10^{6}$ $J/ψ$ events collected by the BESIII detector at the BEPCII collider, a partial-wave analysis of the decay $γγϕ$ is performed to investigate the intermediate resonances in $J/ψ\rightarrowγR, R\arγϕ$. Resonances including $f_{1}(1285)$, $η(1405)$, $f_{1}(1420)$, $f_{1}(1510)$, $f_{2}(1525)$, $X(1835)$, $f_{2}(1950)$, $f_{2}(2010)$, $f_{0}(2200)$ and $η_{c}$ have been detected with statistical significance greater than 5$σ$. The product branching fractions $\mathcal{B}(J/ψ\rightarrowγR, R\ar γϕ)$ are reported, and the resonance parameters of $η(1405)$ and $X(1835)$ have been precisely determined. It is more probable that $η(1405)$ and $X(1835)$ act as the first - and second - excited states of $η^{\prime}$, respectively. The observation of $η_{c}\rightarrowγϕ$ holds great significance for the in depth study of charmonium properties. No evidence of $η(1295)$, $η_{1}(1855)$ or X(2370) is found. The measured upper limits of relevant BF products do not conflict with theoretical expectations for X(2370) as a pseudoscalar glueball and $η_{1}(1855)$ as a hybrid state.

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arXiv2025

Cross section measurement of $e^{+}e^{-} \to f_{1}(1285)π^{+}π^{-}$ at center-of-mass energies between $3.808$ and $4.951\rm GeV$

Using data samples collected by the \mbox{BESIII} detector located at the Beijing Electron Positron Collider, the cross sections of the process $e^+e^-\to f_{1}(1285)π^+π^-$ are measured at forty-five center-of-mass energies from $3.808$ to $4.951 {\rm GeV}$. An investigation on the cross section line shape is performed, and no significant structure is observed.

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arXiv2025

Measurement of the branching fraction of $D^+_s\to \ell^+ν_\ell$ via $e^+e^-\to D^{+}_{s} D^{-}_{s}$

Based on $10.64~\mathrm{fb}^{-1}$ of $e^+e^-$ collision data taken at center-of-mass energies between 4.237 and 4.699 GeV with the BESIII detector, we study the leptonic $D^+_s$ decays using the $e^+e^-\to D^{*+}_{s} D^{*-}_{s}$ process. The branching fractions of $D_s^+\to\ell^+ν_{\ell}\,(\ell=μ,τ)$ are measured to be $\mathcal{B}(D_s^+\toμ^+ν_μ)=(0.547\pm0.026_{\rm stat}\pm0.016_{\rm syst})\%$ and $\mathcal{B}(D_s^+\toτ^+ν_τ)=(5.60\pm0.16_{\rm stat}\pm0.20_{\rm syst})\%$, respectively. The product of the decay constant and Cabibbo-Kobayashi-Maskawa matrix element $|V_{cs}|$ is determined to be $f_{D_s^+}|V_{cs}|=(246.5\pm5.9_{\rm stat}\pm3.6_{\rm syst}\pm0.5_{\rm input})_{μν}~\mathrm{MeV}$ and $f_{D_s^+}|V_{cs}|=(252.7\pm3.6_{\rm stat}\pm4.5_{\rm syst}\pm0.6_{\rm input}))_{τν}~\mathrm{MeV}$, respectively. Taking the value of $|V_{cs}|$ from a global fit in the Standard Model, we obtain ${f_{D^+_s}}=(252.8\pm6.0_{\rm stat}\pm3.7_{\rm syst}\pm0.6_{\rm input})_{μν}$ MeV and ${f_{D^+_s}}=(259.2\pm3.6_{\rm stat}\pm4.5_{\rm syst}\pm0.6_{\rm input})_{τν}$ MeV, respectively. Conversely, taking the value for $f_{D_s^+}$ from the latest lattice quantum chromodynamics calculation, we obtain $|V_{cs}| =(0.986\pm0.023_{\rm stat}\pm0.014_{\rm syst}\pm0.003_{\rm input})_{μν}$ and $|V_{cs}| = (1.011\pm0.014_{\rm stat}\pm0.018_{\rm syst}\pm0.003_{\rm input})_{τν}$, respectively.

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arXiv2025

Measurements of the branching fractions of semileptonic $D^{+}_s$ decays via $e^+e^-\to D_s^{+}D_s^{-}$

We measure the absolute branching fractions of semileptonic $D^+_s$ decays via the $e^+e^-\to D_s^{*+}D_s^{*-}$ process using $e^+e^-$ collision data corresponding to an integrated luminosity of $10.64~\mathrm{fb}^{-1}$ collected by the BESIII detector at center-of-mass energies between 4.237 and 4.699 GeV. The branching fractions are ${\mathcal B}(D_s^+\to ηe^+ν_e)=(2.35\pm0.11_{\rm stat}\pm 0.10_{\rm syst})\%,$ ${\mathcal B}(D_s^+\to η^\prime e^+ν_e)=(0.82\pm0.09_{\rm stat}\pm 0.04_{\rm syst})\%,$ ${\mathcal B}(D_s^+\to ϕe^+ν_e)=(2.21\pm0.16_{\rm stat}\pm 0.11_{\rm syst})\%,$ ${\mathcal B}(D_s^+\to f_0(980) e^+ν_e,f_0(980)\toπ^+π^-)=(0.15\pm0.02_{\rm stat}\pm 0.01_{\rm syst})\%,$ ${\mathcal B}(D_s^+\to K^0 e^+ν_e)=(0.24\pm0.04_{\rm stat}\pm 0.01_{\rm syst})\%,$ and ${\mathcal B}(D_s^+\to K^{*0} e^+ν_e)=(0.19\pm0.03_{\rm stat}\pm 0.01_{\rm syst})\%.$ These results are consistent with those measured via the $e^+e^-\to D_s^{*\pm}D_s^{\mp}$ process by BESIII and CLEO. The hadronic transition form factors $D^+_s\to ηe^+ν_e$, $D^+_s\to η^\prime e^+ν_e$, and $D^+_s\to K^0 e^+ν_e$ at four-momentum transfer squared $q^2$ = 0 are determined to be $f^η_+(0) = 0.482 \pm 0.011_{\rm stat} \pm 0.009_{\rm syst}\pm0.004_{\rm input},$ $f^{η^{\prime}}_+(0) = 0.562 \pm 0.031_{\rm stat} \pm 0.014_{\rm syst}\pm0.003_{\rm input},$ and $f^{K^0}_+(0) = 0.624 \pm 0.052_{\rm stat} \pm 0.013_{\rm syst}\pm0.002_{\rm input}.$

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arXiv2025

Test of lepton universality and measurement of the form factors of $D^0\to K^{*}(892)^-μ^+ν_μ$

We report a first study of the semileptonic decay $D^0\rightarrow K^-π^0μ^{+}ν_μ$ by analyzing an $e^+e^-$ annihilation data sample of $7.9~\mathrm{fb}^{-1}$ collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. The absolute branching fraction of $D^0\to K^-π^0μ^{+}ν_μ$ is measured for the first time to be $(0.729 \pm 0.014_{\rm stat} \pm 0.011_{\rm syst})\%$. Based on an amplitude analysis, the $S\text{-}{\rm wave}$ contribution is determined to be $(5.76 \pm 0.35_{\rm stat} \pm 0.29_{\rm syst})\%$ of the total decay rate in addition to the dominated $K^{*}(892)^-$ component. The branching fraction of $D^0\to K^{*}(892)^-μ^+ν_μ$ is given to be $(2.062 \pm 0.039_{\rm stat} \pm 0.032_{\rm syst})\%$, which improves the precision of the world average by a factor of 5. Combining with the world average of ${\mathcal B}(D^0\to K^{*}(892)^-e^+ν_e)$, the ratio of the branching fractions obtained is $\frac{{\mathcal B}(D^0\to K^{*}(892)^-μ^+ν_μ)}{{\mathcal B}(D^0\to K^{*}(892)^-e^+ν_e)} = 0.96\pm0.08$, in agreement with lepton flavor universality. Furthermore, assuming single-pole dominance parameterization, the most precise hadronic form factor ratios for $D^0\to K^{*}(892)^{-} μ^+ν_μ$ are extracted to be $r_{V}=V(0)/A_1(0)=1.37 \pm 0.09_{\rm stat} \pm 0.03_{\rm syst}$ and $r_{2}=A_2(0)/A_1(0)=0.76 \pm 0.06_{\rm stat} \pm 0.02_{\rm syst}$.

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arXiv2025

Observation of $Λ_c^+ \to Λa_0(980)^+$ and Evidence for $Σ(1380)^+$ in $Λ_c^+ \to Λπ^+ η$

Based on $6.1~\mathrm{fb}^{-1}$ of $e^+e^-$ annihilation data collected at center-of-mass energies from 4.600 to 4.843 GeV with the BESIII detector at the BEPCII collider, a partial wave analysis of $Λ_c^+\toΛπ^+η$ is performed, and branching fractions and decay asymmetry parameters of intermediate processes are determined. The process $Λ_c^+\toΛa_0(980)^+$ is observed for the first time, and evidence for the pentaquark candidate $Σ(1380)^+$ decaying into $Λπ^+$ is found with statistical significance larger than $3σ$ with mass and width fixed to theoretical predictions. The branching fraction product $\mathcal{B}[Λ_{c}^{+} \to Λa_0(980)^+] \; \mathcal{B}[ a_0(980)^+ \to π^{+}η]$ is determined to be $(1.05 \pm 0.16_{\mathrm{stat}} \pm 0.05_{\mathrm{syst}} \pm 0.07_{\mathrm{ext}})\%$, which is larger than theoretical calculations by 1-2 orders of magnitude. Here the third (external) systematic is from $\mathcal{B}(Λ_{c}^{+} \to Λπ^+ η)$. Finally, we precisely obtain the absolute branching fraction $\mathcal{B}(Λ_{c}^{+} \to Λπ^+ η) = (1.94 \pm 0.07_{\mathrm{stat}} \pm 0.11_{\mathrm{syst}})\%$.

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arXiv2025

Observation of a rare beta decay of the charmed baryon with a Graph Neural Network

The beta decay of the lightest charmed baryon $Λ_c^+$ provides unique insights into the fundamental mechanism of strong and electro-weak interactions, serving as a testbed for investigating non-perturbative quantum chromodynamics and constraining the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameters. This article presents the first observation of the Cabibbo-suppressed decay $Λ_c^+ \rightarrow n e^+ ν_{e}$, utilizing $4.5~\mathrm{fb}^{-1}$ of electron-positron annihilation data collected with the BESIII detector. A novel Graph Neural Network based technique effectively separates signals from dominant backgrounds, notably $Λ_c^+ \rightarrow Λe^+ ν_{e}$, achieving a statistical significance exceeding $10σ$. The absolute branching fraction is measured to be $(3.57\pm0.34_{\mathrm{stat.}}\pm0.14_{\mathrm{syst.}})\times 10^{-3}$. For the first time, the CKM matrix element $\left|V_{cd}\right|$ is extracted via a charmed baryon decay as $0.208\pm0.011_{\rm exp.}\pm0.007_{\rm LQCD}\pm0.001_{τ_{Λ_c^+}}$. This work highlights a new approach to further understand fundamental interactions in the charmed baryon sector, and showcases the power of modern machine learning techniques in experimental high-energy physics.

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arXiv2025

Search for $η_c(2S)\to p\bar{p}K^+K^-$ and measurement of $χ_{cJ}\to p\bar{p}K^+K^-$ in $ψ(3686)$ radiative decays

A search for $η_c(2S)\to p\bar{p}K^+K^-$, together with measurement of branching fractions of $χ_{cJ(J=0,1,2)}\to p\bar{p}K^+K^-$ in the $ψ(3686) \to γη_c(2S)$ and the $ψ(3686) \to γχ_{cJ}$ radiative decays, is performed with $(2712.4\pm14.3)\times 10^6$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider. An evidence for $η_c(2S)\to p\bar{p}K^+K^-$ is found, with a significance of $3.3σ$. The product branching fraction of $\mathcal{B}[ψ(3686)\toγη_c(2S)]\cdot\mathcal{B}[η_c(2S)\to p\bar{p}K^+K^-]$ is determined to be $(1.98\mkern 2mu\pm\mkern 2mu0.41_{\text{stat.}}\mkern 2mu\pm\mkern 2mu0.99_{\text{syst.}})\times 10^{-7}$. The product branching fractions of $\mathcal{B}[ψ(3686)\toγχ_{cJ}]\cdot\mathcal{B}[χ_{cJ}\to p\bar{p}K^+K^-]$ are measured to be $(2.49\mkern 2mu\pm\mkern 2mu 0.03_{\text{stat.}}\mkern 2mu\pm\mkern 2mu 0.15_{\text{syst.}})\times 10^{-5}$, $(1.83\mkern 2mu \pm\mkern 2mu 0.02_{\text{stat.}}\mkern 2mu \pm\mkern 2mu 0.11_{\text{syst.}})\times 10^{-5}$, and $(2.43\mkern 2mu\pm\mkern 2mu 0.02_{\text{stat.}}\mkern 2mu\pm\mkern 2mu 0.15_{\text{syst.}})\times 10^{-5}$, for $J=0,\ 1$, and 2, respectively.

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arXiv2024

$\mathcal R(3780)$ Resonance Interpreted as the $1^3D_1$-Wave Dominant State of Charmonium from Precise Measurements of the Cross Section of $e^+e^-\rightarrow$ Hadrons

We report the precise measurements of the cross section of $e^+e^-\rightarrow$ hadrons at center-of-mass energies from 3.645 to 3.871 GeV. We thereby perform the most precise study of the cross sections and find a complex system composed of three resonances of $\mathcal R(3760)$, $\mathcal R(3780)$, and $\mathcal R(3810)$. For the first time, we measure the $\mathcal R(3810)$ electronic width to be $(19.4 \pm 7.4 \pm 12.1)$ eV. For the $\mathcal R(3760)$ resonance, we measure the mass to be $(3751.9\pm 3.8\pm 2.8)$ MeV/$c^2$, the total width to be $(32.8 \pm 5.8 \pm 8.7)$ MeV, and the electronic width to be $(184\pm 75\pm 86)$ eV. For the $\mathcal R(3780)$ resonance, we measure its mass to be $(3778.7\pm 0.5\pm 0.3)$ MeV/$c^2$, total width to be $(20.3 \pm 0.8 \pm 1.7)$ MeV, and electronic width to be $(265\pm 67\pm 83)$ eV. Forty-seven years ago, the $ψ(3770)$ resonance was discovered, and was subsequently interpreted as the $1^3D_1$-wave dominant state of charmonium. However, our analysis of the total-hadron cross sections indicates that the $ψ(3770)$ is not a single state, but a complex system composed of the $\mathcal R(3760)$, $\mathcal R(3780)$, and $\mathcal R(3810)$ resonances. Among these, we interpret the $\mathcal R(3780)$ is a resonance dominated by the $1^3D_1$ charmonium state.

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arXiv2024

Measurement of $Σ^+$ transverse polarization in $e^+e^-$ collisions at $\sqrt{s} = 3.68-3.71$ GeV

Using $e^+e^-$ collision data collected with the BESIII detector at seven energy points ranging from 3.68 to 3.71 GeV and corresponding to an integrated luminosity of $652.1~{\rm pb^{-1}}$, we present an energy-dependent measurement of the transverse polarization, relative phase and modulus ratio of the electromagnetic form factors of the $Σ^+$ hyperon in the $e^+e^- \to Σ^+ \barΣ^-$ reaction. These results are helpful to understand the production mechanism of the $Σ^+$-$\barΣ^-$ pairs.

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arXiv2024

Search for the double Dalitz decays $η/η' \to e^+e^-μ^+μ^-$ and $η' \to μ^+μ^-μ^+μ^-$

Using a data sample of $(10087 \pm 44) \times {10^{6}}$ $J/ψ$ events collected with the BESIII detector, we search for the decays $η/η'\to e^+e^-μ^+μ^-$ and $η' \to μ^+μ^-μ^+μ^-$ via the radiative decays $J/ψ\toγη$/$γη'$. No excess of events over expected background is observed for any of the decays of interest. At 90% confidence level, we report the first upper limits on the branching fractions of $η' \to e^{+}e^{-}μ^{+}μ^{-}$ and $η' \to μ^{+}μ^{-}μ^{+}μ^{-}$ to be $ 1.75 \times {10^{-6}}$ and $5.28 \times {10^{-7}}$, respectively. In addition, we set an upper limit on the branching fraction of $η\to e^{+}e^{-}μ^{+}μ^{-}$ to be $6.88 \times {10^{-6}}$, which improves the previous result by about two orders of magnitude.

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