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BESIII Collaboration

Publications and source records attributed to BESIII Collaboration.

At least 37 records · Page 2Linked to original sources

arXiv2026

Study of $K_{S}^{0}$-$K_{L}^{0}$ asymmetry in the decays $D^0 \to K_{S}^{0}ω$ and $D^0 \to K_{L}^{0} ω$

Based on $e^+ e^-$ annihilation data corresponding to an integrated luminosity of 7.93~$fb^{-1}$ collected at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider, the absolute branching fractions of the decays $D^0 \to K_{S}^{0} ω$ and $D^0 \to K_{L}^{0} ω$ are measured to be $(11.79 \pm 0.19 \pm 0.26 \pm 0.47) \times 10^{-3}$ and ($10.84 \pm 0.14 \pm 0.23 \pm 0.44) \times 10^{-3}$, respectively. The $K_{S}^{0}- K_{L}^{0}$ branching-fraction asymmetry of these two decays is $R(D^0,K_{S,L}^{0} ω) = \frac{\mathcal{B}(D^0 \to K_{S}^{0} ω) - \mathcal{B}(D^0 \to K_{L}^{0}ω)}{\mathcal{B}(D^0 \to K_{S}^{0} ω) + \mathcal{B}(D^0 \to K_{L}^{0} ω)} =(4.2 \pm 1.0 \pm 0.9 \pm 2.8)\%$. Here, the first uncertainties are statistical, the second systematic, and the third arise from the interference between $D^0 \to K_{S,L}^{0} ω$ and the non-resonant $D^0 \to π^+ π^- π^0 K_{S,L}^{0}$ processes.

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arXiv2026

Search for the baryonic decay $ D_{s}^{*+} \to \ p \bar{n} $

The first search for the baryonic decay $ D_{s}^{*+} \to \ p \bar{n} $ is performed using $e^+e^-$ collision data taken at center-of-mass energies between 4.128 and 4.226 GeV, collected by the BESIII experiment and corresponding to an integrated luminosity of 7.33 fb$^{-1}$. No significant signal is observed, and an upper limit on the branching fraction is set to be $1.3\times 10^{-4}$ at the $90\%$ confidence level.

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arXiv2026

Observation of $ψ(3686)\to p K^- K_S^0 \bar Ξ^0+c.c.$

Using a sample of $(2.712 \pm 0.014) \times 10^{9}$ $ψ(3686)$ events collected with the BESIII detector, the decay of $ψ(3686)\to p K^- K_S^0 \bar Ξ^0+c.c.$ is observed for the first time with a statistical significance of $11.5σ$. The branching fraction of this decay is measured to be $(2.84\pm 0.40\pm 0.25) \times 10^{-6}$, where the first and second uncertainties are statistical and systematic, respectively. This measurement extends the experimental information on rare multi-strange $ψ(3686)$ decays and provides an experimental reference for future studies of related decay modes.

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arXiv2026

Measurement of inelastic scattering $Λ(\overlineΛ)+p\toΣ^{0}(\overlineΣ^{0})+p$ via $e^+e^-\to J/ψ\toΛ\overlineΛ$

Using a sample of $(10087\pm44)\times10^{6}$ $J/ψ$ events collected with the BESIII detector, we investigate the inelastic scattering processes $Λ+p\toΣ^{0}+p$ and $\overlineΛ+p\to\overlineΣ^{0}+p$, exploiting hyperons from $J/ψ\toΛ\overlineΛ$ decays as an effective beam and the beam-pipe materials as targets. The processes $Λ+{}^{9}\mathrm{Be}\toΣ^{0}+p+{}^{8}\mathrm{Li}$ and $\overlineΛ+{}^{9}\mathrm{Be}\to\overlineΣ^{0}+p+{}^{8}\mathrm{Li}$ are measured at a hyperon momentum of $1.074~\mathrm{GeV}/c$, with cross sections of $(10.1\pm1.4_{\rm stat}\pm0.7_{\rm syst})$ mb and $(1.7\pm0.6_{\rm stat}\pm0.4_{\rm syst})$ mb, respectively. Under the assumption of surface-dominated hyperon-nucleus scattering, these measurements are used to extract the corresponding proton-target cross sections. Independently, direct measurements using the hydrogen component of the beam-pipe oil yield $(3.2\pm1.1_{\rm stat}\pm0.5_{\rm syst})$ mb for $Λ+p\toΣ^{0}+p$ and $(1.5\pm0.5_{\rm stat}\pm0.1_{\rm syst})$ mb for $\overlineΛ+p\to\overlineΣ^{0}+p$, consistent with the indirect determinations. The combined cross sections are $(4.7\pm0.7)$ mb and $(1.1\pm0.3)$ mb, respectively. The $\overlineΛ+p\to\overlineΣ^{0}+p$ signal constitutes the first evidence for anti-hyperon inelastic scattering with baryonic final states, with a significance of $3.1σ$. The pronounced difference between the $Λp$ and $\overlineΛp$ inelastic scattering cross sections provides new experimental constraints on hyperon-nucleon and anti-hyperon-nucleon interactions.

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arXiv2026

Observation of the $X(2370)$ in $J/ψ\rightarrowγK^{0}_{S}K^{0}_{S}π^{0}$ and $J/ψ\rightarrowγπ^{0}π^{0}η$

Based on $(10087\pm44)\times10^{6}$ $J/ψ$ events collected with the BESIII detector, the $J/ψ\rightarrowγK^{0}_{S}K^{0}_{S}π^{0}$ and $J/ψ\rightarrowγπ^{0}π^{0}η$ processes are studied. The $X(2370)$ is observed in both the $K^{0}_{S}K^{0}_{S}π^{0}$ and $π^{0}π^{0}η$ invariant mass spectra, with statistical significances greater than $14σ$ and $20σ$, respectively. By combining measurements from these processes with those from the previously reported $J/ψ\rightarrowγK^{0}_{S}K^{0}_{S}η^{\prime}$ process, the mass and width of the $X(2370)$ are determined to be $2359^{+13}_{-14}~\text{MeV}/c^{2}$ and $170^{+44}_{-29}~\text{MeV}$, respectively. In addition, the decay $X(2370)\to a_{0}(980)^{0}π^{0}$ with $a_{0}(980)^{0}\to π^{0}η$ is observed with a statistical significance exceeding $9σ$. The properties of the $X(2370)$\textemdash decay pattern similarities to that of $η_{c}$, are consistent with those of a pseudoscalar glueball.

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arXiv2026

Production and Decay Dynamics of the Charmed Baryon $Λ_c^+$ in $e^+e^-$ Annihilations near Threshold

The study of the charmed baryons is crucial for investigating the strong and weak interactions in the standard model and for gaining insights into the internal structure of baryons. In an $e^+e^-$ experiment the lightest charmed baryon, $Λ_c^+$, can be produced in pairs through the single-photon annihilation process. This process can be described by two complex electromagnetic form factors. The presence of a nonzero relative phase between these form factors gives rise to a transverse polarization of the charmed baryon and provides additional constraints on the dynamic parameters in the decays. In this article, we present the first observation of the transverse polarization of $Λ_{c}^{+}$ in the reaction $e^+e^- \to Λ_c^{+}\barΛ_c^-$, based on $6.4~\text{fb}^{-1}$ of $e^{+}e^{-}$ annihilation data collected at center-of-mass energies between $4600$~MeV and $4951$~MeV with the BESIII detector. The decay asymmetry parameters in the decays $Λ_c^+ \to pK_S^0$, $Λπ^+$, $Σ^0π^+$, and $Σ^+π^0$ are simultaneously extracted from the joint angular distributions. By independently extracting the above parameters for the process and its $C\!P$-conjugate counterpart, we derive both the strong and weak phase differences between different partial waves, and test several $C\!P$ observables. The obtained results fully demonstrate the feasibility of exploiting transverse polarization at electron-positron colliders to search for $C\!P$-violating effects, opening up a new avenue for exploring $C\!P$ violation in the charmed baryon sector.

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arXiv2026

Observation of the $χ_{cJ}$ decays into $pK^{-}\barΛη+\mathrm{c.c.}$

By analyzing $(2712.4 \pm 14.3) \times 10^{6}$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decays $χ_{cJ} \to pK^{-}\barΛη+ \mathrm{c.c.}$ ($J=0,1,2$) are observed for the first time, with statistical significances exceeding $5σ$ for all three $χ_{cJ}$ states. The measured branching fractions are $\mathcal{B}(χ_{c0} \to pK^{-}\barΛη+ \mathrm{c.c.}) = (5.3 \pm 0.7 \pm 0.5) \times 10^{-5}$, $\mathcal{B}(χ_{c1} \to pK^{-}\barΛη+ \mathrm{c.c.}) = (9.8 \pm 0.6 \pm 0.6) \times 10^{-5}$, and $\mathcal{B}(χ_{c2} \to pK^{-}\barΛη+ \mathrm{c.c.}) = (9.3 \pm 0.6 \pm 0.6) \times 10^{-5}$, where the first uncertainties are statistical and the second are systematic. Structures consistent with the known hyperon resonances $Λ(1520)$ and $\barΛ(1690)$ are seen in the $pK^{-}$ and $\barΛη$ invariant mass spectra, respectively. The reported branching fractions include both resonant and non-resonant contributions. These results provide new experimental information on hadronic decays of $P$-wave charmonium states and contribute to the understanding of baryon production and hadronization dynamics in the nonperturbative QCD regime.

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arXiv2026

Evidence for $η_{c}(2S)\to p\bar{p}π^{+}π^{-}π^{0}$ and observation of $χ_{cJ} \to p\bar{p}π^{+}π^{-}π^{0}$

Using $(2.712\pm0.014)\times 10^9$ $ψ(3686)$ events collected by the BESIII detector at the BEPCII collider, the $ψ(3686) \to γp\bar{p}π^+π^-π^0$ process is investigated. Evidence for the decay of $η_{c}(2S)\to p\bar{p}π^{+}π^{-}π^{0}$ is found with a signal significance of 3.3$σ$. The product of branching fractions of $\mathcal{B}[ψ(3686)\to γη_{c}(2S)]\times\mathcal{B}[η_{c}(2S)\to p\bar{p}π^{+}π^{-}π^{0}]$ is determined to be $(3.4\pm0.5\pm0.8) \times 10^{-6}$, where the first uncertainty is statistical and the second systematic. The hadronic decays of $χ_{cJ} \to p\bar{p}π^+π^-π^0$$~(J=0,1,2)$ are observed, and their branching fractions are measured to be $\mathcal{B}(χ_{c0}\to p\bar{p}π^{+}π^{-}π^{0})=(4.79\pm 0.01\pm0.40) \times 10^{-3}$, $\mathcal{B}(χ_{c1}\to p\bar{p}π^{+}π^{-}π^{0})=(2.13\pm 0.01\pm0.17) \times 10^{-3}$, and $\mathcal{B}(χ_{c2}\to p\bar{p}π^{+}π^{-}π^{0})=(3.72\pm 0.01\pm0.29) \times 10^{-3}$, respectively. Furthermore, the branching fractions for the intermediate processes $χ_{cJ}\to p\bar{p}ω$ are updated with significantly improved precision: $\mathcal{B}(χ_{c0}\to p\bar{p}ω)=(5.76\pm0.01\pm0.42)\times10^{-4}$, $\mathcal{B}(χ_{c1}\to p\bar{p}ω)=(1.85\pm0.01\pm0.13)\times10^{-4}$, and $\mathcal{B}(χ_{c2}\to p\bar{p}ω)=(4.51\pm0.01\pm0.33)\times10^{-4}$, respectively.

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arXiv2026

Measurement of branching fractions of $D^+_s\to K^0_SK^0_S π^+π^0$ and $D^+_s\to K^0_S K^+π^0π^0$

By analyzing $e^+e^-$ collision data corresponding to an integrated luminosity of 7.33~fb$^{-1}$ collected with the BESIII detector at center-of-mass energies ranging from 4.128 to 4.226~GeV, we report the observations of the hadronic decays $D^+_s\to K^0_SK^0_Sπ^+π^0$ and $D^+_s\to K^0_S K^+π^0π^0$. Their decay branching fractions are determined to be ${\mathcal B}(D^+_s\to K^0_SK^0_S π^+π^0)=(4.08\pm0.46_{\rm stat}\pm0.45_{\rm syst})\times 10^{-3}$ and ${\mathcal B}(D^+_s\to K^0_S K^+π^0π^0)=(3.32\pm0.64_{\rm stat}\pm0.31_{\rm syst})\times 10^{-3}$, where the first uncertainties are statistical and the second are systematic.

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arXiv2026

Amplitude Analysis of Singly Cabibbo-Suppressed Decay $Λ^{+}_{c}\to p K^{+} K^{-}$

Using a sample of $e^{+}e^{-}$ annihilation data corresponding to an integrated luminosity of 4.4 $\rm{fb}^{-1}$ collected with the BESIII detector at the BEPCII collider and produced at center-of-mass energies from $4600$ to $4698~\rm{MeV}$, an amplitude analysis is performed of the singly Cabibbo-suppressed decay $Λ^{+}_{c}\to pK^{+}K^{-}$. The branching fractions of $Λ^{+}_{c}\to pϕ(1020)$, $pf_{0}(980)$, $Λ(1405)K^{+}$, and $Λ(1670)K^{+}$ are measured, where the latter two modes are decays that are observed for the first time. At the same time, with the detection efficiency based on the results of the amplitude analysis, the branching fraction of $Λ^{+}_{c}\to pK^{+}K^{-}$ is updated to be $(9.94\pm0.65_{\text{stat.}}\pm0.50_{\text{syst.}})\times10^{-4}$, which is consistent with the current world average value within one standard deviation. The result supersedes the previous BESIII measurement with precision improved by approximately a factor of 1.5.

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arXiv2026

Measurement of Branching Fraction and Transition Magnetic Moment of the Hyperon Dalitz Decay $Σ^0 \rightarrow Λe^+e^-$

Based on a data sample of 10 billion $J/ψ$ events collected with the BESIII detector operating at the BEPCII collider, the Dalitz decay $Σ^0 \rightarrow Λe^+e^-$ is studied experimentally for the first time. The $Σ^0$ hyperons are produced through the process $J/ψ\rightarrow Σ^0\barΣ^0$ and analyzed using a double-tag method. The absolute branching fraction is measured to be $\mathcal{B}(Σ^0 \rightarrow Λe^+e^-) = (6.34 \pm 0.25_{\rm stat.} \pm 0.23_{\rm syst.}) \times 10^{-3}$. This result shows a $2σ$ discrepancy from the theoretical calculation quoted in the PDG, where the uncertainties are statistical and systematic, respectively. In addition to the branching fraction, the transition magnetic moment $μ$ is determined to be $(1.74 \pm 0.03_{\rm stat.} \pm 0.09_{\rm syst.})\,μ_N$, where $μ_N=e/(2m_p)$ represents the nucleon magnetic moment, providing valuable insight into the intrinsic structure of the $Σ^0$ hyperon.

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arXiv2026

First measurements of the branching fractions of $J/ψ$ and $ψ(3686) \to Σ^{0} \barΣ^{0}η$

Based on $(10087 \pm 44) \times 10^6$ $J/ψ$ and $(2712 \pm 14) \times 10^6$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, the hadronic decays $J/ψ\to Σ^{0} \barΣ^{0} η$ and $ψ(3686) \to Σ^{0} \barΣ^{0} η$ are observed for the first time. The corresponding branching fractions are measured to be $\mathcal{B}(J/ψ\to Σ^{0} \barΣ^{0}η)= (7.5 \pm 0.3 \pm 0.8) \times 10^{-5}$ and $\mathcal{B}(ψ(3686) \to Σ^{0} \barΣ^{0}η)= (1.3\pm 0.1 \pm 0.1) \times 10^{-5}$, respectively, where the first uncertainties are statistical, and the second systematic. The ratio $\text{Q} \approx \frac{\mathcal{B}(ψ(3686) \to Σ^{0} \barΣ^{0} η)}{\mathcal{B}(J/ψ\to Σ^{0} \barΣ^{0} η)}$ is determined to be $(17.3 \pm 1.5 \pm 1.7)\%$, which is con sistent with the 12\%-rule within 3.0$σ$.~No significant intermediate states or threshold enhancements are observed in the $Σ^0$($\barΣ^{0}$)$η$ and $Σ^0$$\barΣ^{0}$ invariant mass spectra.

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arXiv2026

High-precision measurement of the space-like $η^\prime$ transition form factor

Using a data sample corresponding to an integrated luminosity of $20.3\ \text{fb}^{-1}$, collected with the BESIII detector at a center-of-mass energy of $3.773\ \text{GeV}$ at the BEPCII collider, we report a precision measurement of the product $Q^2|F(Q^2)|$, where $F(Q^2)$ is the single-virtual space-like transition form factor of the $η'$ meson and $Q^2$ is the squared momentum transfer of the tagged virtual photon. The transition form factor is extracted from the differential Born cross section of the two-photon fusion processes $e^+e^- \to e^+e^-γγ^* \to e^+e^-η^\prime$ using a single-tag technique, where only one scattered lepton is detected. The measurement covers $Q^2 \in [0.1, 6.0]$ GeV$^2$, achieving unprecedented precision, better than $3.0\%$ for $Q^2 < 1.5$ GeV$^2$, and providing the first direct determination at $Q^2 < 0.3$ GeV$^2$.

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arXiv2026

Observation of $Λ^+_c\to nπ^+η$ and search for $Λ^+_c\to na_0(980)^+$

By analysing 6.1 ${\rm fb}^{-1}$ of data collected at center-of-mass energies between $\sqrt{s}=4.600$ and 4.843 $\rm GeV$ with the BESIII detector at the BEPCII collider, we observe the decay $Λ_c^+\to nπ^+η$ for the first time with a statistical significance of $9.5σ$. The ratio of branching fractions $\mathcal{B}(Λ_c^+\to nπ^+η)/\mathcal{B}(Λ_c^+\to Λπ^+η)$ is measured to be $0.155\pm0.031_{\rm stat.}\pm0.012_{\rm syst.}$ Taking the world average of $\mathcal{B}(Λ_c^+\to Λπ^+η)$ as reference, the absolute branching fraction is calculated to be $\mathcal{B}(Λ_c^+\to nπ^+η)=(2.94\pm0.59_{\rm stat.}\pm0.23_{\rm syst.}\pm0.13_{\rm ref.})\times10^{-3}$. The intermediate process $Λ_c^+\to na_0(980)^+$ is also searched for in the $π^+η$ invariant mass spectrum. Since no significant signal is found, the upper limit on $\mathcal{B}(Λ_c^+\to na_0(980)^+)\times\mathcal{B}(a_0(980)^+\toπ^+η)$ is set to $8.4\times10^{-4}$ at 90\% confidence level. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish signals from prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification.

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arXiv2026

Search for the charged lepton flavour violating decay $η'\to eμ$

Based on $(8998\pm40)\times10^6$ $J/ψ$ events collected in $e^+e^-$ collisions at $\sqrt{s} = 3.097$ GeV with the BESIII detector, we present a search for the charged lepton flavour violating decay $η'\to eμ$ with $J/ψ\toγη'$. No significant signal is observed, and an upper limit on its decay branching fraction is set to be $6.3\times10^{-7}$ at the 90% confidence level, improving the previous best result by nearly three orders of magnitude.

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arXiv2026

Observation of a Charged Charmoniumlike Structure in $e^+e^-\rightarrow D^0D^-π^++c.c.$

We present a partial wave analysis of the process $e^+e^- \rightarrow D^0 D^- π^++c.c.$ using a data sample collected with the BESIII detector at a center-of-mass energy of 4682~MeV. A charged structure, referred to as the $X(3790)^-$ near the $D^0D^-$ mass threshold with a significance of $5.3σ$, which includes systematic uncertainties and the look-elsewhere effect. Assuming a Flatté description of the structure, the quantum numbers of the $X(3790)^-$ are found to be $J^{P}=1^{-}$, and its mass and coupling strength to the $D^0D^-$ channel are determined to be $(3794.7 \pm 6.0 \pm 8.7)$~MeV/$c^2$ and $(1.6 \pm 0.2 \pm 0.2)$~GeV, respectively, where the first uncertainties are statistical and the second systematic. In addition, we also report measurements of the masses and widths of the $D_{2}^{*}(2460)$, $D_{1}^{*}(2600)$, and $D_{1}^{*}(2760)$ charmed mesons.

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arXiv2026

First energy scan measurement of $e^{+}e^{-}\to K^{+}K^{-}$ around the $ψ(2S)$ resonance

We report the precise energy scan measurement of the cross section lineshape of $ψ(2S)\to K^{+}K^{-}$. The analysis is based on $e^{+}e^{-}$ collision data corresponding to an integrated luminosity of 495~pb$^{-1}$ collected with the BESIII detector at BEPCII. By analyzing the cross section line-shape, we extract the relative phase $Φ$ between the strong and electromagnetic amplitudes of the $ψ(2S)$ resonance, a fundamental parameter in charmonium physics, based on the assumption that the relative phase between the electromagnetic amplitude of the $ψ(2S)$ resonance and the continuum is zero. Two distinct solutions for the branching fraction $\mathcal{B}$ of $ψ(2S)\to K^{+}K^{-}$ are observed: a constructive interference solution with $\mathcal{B}=(7.49\pm0.41)\times10^{-5}$ and $Φ=(110.1 \pm6.7)^\circ$, and a destructive interference solution with $\mathcal{B}=(10.94\pm0.48)\times10^{-5}$ and $Φ=(-106.8\pm5.7)^\circ$. A significant correlation between $Φ$ and $\mathcal{B}$ is established, demonstrating that interference effects must be taken into account in the $ψ(2S)$ branching fraction measurements. Additionally, the first results for both the $ψ(2S)$ strong form factor, which characterizes the strong coupling between $ψ(2S)$ and $K^{+}K^{-}$, and the energy-dependent electromagnetic form factor of the charged kaon in this energy region are reported.

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arXiv2026

Precision measurements of semleptonic decays $D^0 \to π^-\ell^+ν_\ell$ and $D^+ \to π^0\ell^+ν_\ell$ ($\ell =e,μ$)

The branching fractions of $D^0\to π^-e^+ν_e$, $D^0\to π^-μ^+ν_μ$, $D^+\to π^0e^+ν_e$, and $D^+\to π^0μ^+ν_μ$ are measured to be $(2.950\pm0.017_{\rm stat.}\pm 0.017_{\rm syst.})\times10^{-3}$, $(2.817\pm0.037_{\rm stat.}\pm 0.019_{\rm syst.})\times10^{-3}$, $(3.622\pm0.034_{\rm stat.}\pm 0.018_{\rm syst.})\times10^{-3}$, and $(3.507\pm0.043_{\rm stat.}\pm 0.026_{\rm syst.})\times10^{-3}$ using $e^+e^-$ collision data with an integrated luminosity of 20.3 fb$^{-1}$ collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. The partial decay rates of these four decays are measured with the best precision to date and their forward-backward asymmetries are determined for the first time. By performing a simultaneous fit to these results, the product of the hadronic transition form factor $f^{D\toπ}_+(0)$ and the modulus of the $c\to d$ Cabibbo-Kobayashi-Maskawa matrix element $|V_{cd}|$ is given by $f^{D\toπ}_+(0)|V_{cd}|=0.1425\pm0.0005_{\rm stat.}\pm0.0003_{\rm syst.}$. Taking the $|V_{cd}|$ provided by the standard model global fit and the $f^{D\toπ}_+(0)$ calculated from the lattice quantum chromodynamics as input, we obtain $f^{D\toπ}_+(0)=0.6339\pm0.0024_{\rm stat.}\pm0.0014_{\rm syst.}$ and $|V_{cd}|=0.2262\pm0.0008_{\rm stat.}\pm0.0005_{\rm syst.}\pm0.0018_{\rm LQCD.}$, respectively. The reported results have the best precision to date. We also search for the scalar current contribution in the $c\to d \ell^+ν_{\ell}$ transition and determine Re$(C_S^μ)=$ $0.022 \pm 0.023_{\rm stat.}\pm 0.003_{\rm syst.}$ and $|{\rm Im}(C_S^μ)|=0.000 \pm $ $0.038_{\rm stat.} \pm 0.012_{\rm syst.}$. In addition, the lepton flavor universality is tested with the ratios of the decay rates between semimuonic and semielectronic decays in full and several $\ell^+ν_\ell$ four-momentum transfer ranges.

hep-ex↗