News&Events

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  Quantum-entangled hyperons open a new route to testing the Standard Model BESIII pioneers a study of baryon semileptonic decays through polarization and quantum entanglement, including the first semileptonic form-factor measurements for an antihyperon.
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  First observation of D⁰⁽⁺⁾ → K̅ ω e⁺ νₑ decays and experimental evidence for the two-pole structure of K̅₁(1270)
  
  The BESIII collaboration recently reported the first observation of the semileptonic decays D⁰ → K⁻ ω e⁺ νₑ and D⁺ → K_S⁰ ω e⁺ νₑ with significances of 8.0σ and 5.8σ, respectively. The measurement is based on 20.3 fb⁻¹ of e⁺ e⁻ annihilation data collected at a center-of-mass energy of 3.773 GeV. This work provides the most precise measurement of the branching fraction (BF) of K̅₁(1270) → K̅ ω decay from a collider experiment to date, and offers unique experimental evidence for the two-pole structure of the K̅₁(1270) resonance. The results have been published recently in Physical Review Letters on 26 August, 2026 [Phys. Rev. Lett. 137, 091802].
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  First Experimental Constraint on the Scalar Current and Precise measurements of D⁰⁽⁺⁾ → K̅ l⁺ νₗ decays The BESIII collaboration has reported "First Experimental Constraint on the Scalar Current in the D⁰⁽⁺⁾ → K̅ l⁺ νₗ Transition" and "Precise measurements of D⁰ → K⁻ l⁺ νₗ and D⁺ → K̅⁰ l⁺ νₗ decays". These results have been published in Physical Review Letters [Phys. Rev. Lett. 137, 091803 (2026)], accompanied by a detailed companion paper in Physical Review D [Phys. Rev. D. 114, 033008 (2026)] on 27 Aug 2026.
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  The first measurement of the semileptonic decay Ξ⁻ → Λ e⁻ νbar_e at an electron-positron collider The BESIII Collaboration has reported the first measurement of the semileptonic decay Ξ⁻ → Λ e⁻ νbare at an electron-positron collider, providing the first determination of its absolute branching fraction, as well as the first update of the Ξ⁻ axial charge in more than four decades. The result has been published in Physical Review Letters [Phys. Rev. Lett. 137, 091801 (2026)].
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  BESIII Experiment Identifies X(2370) as a Glueball-dominated Particle At the International Conference on High Energy Physics held in Brazil, the BESIII Collaboration at the Beijing Electron Positron Collider announced in a special plenary report that after fifteen years of sustained research, the BESIII Collaboration identified that the dominant constituent of the X(2370) is a pseudoscalar glueball with spin-parity quantum numbers of 0⁻⁺.
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  BESIII Sets New Bound for Sub-GeV Dark Matter Interactions The BESIII Collaboration recently reports the search for sub-GeV dark particles in η→π⁰+invisible decay and provides a new bound for the sub-GeV dark matter, which has been published in Physical Review Letters on 16th July, 2026 [Phys. Rev. Lett. 137, 031804] as PRL Editors Suggestion.
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  BESIII Reports First Measurements of Antineutron–Proton Annihilation into Multi-Pion Final States Recently, the BESIII collaboration has reported new results on antineutron–proton interactions by measuring the annihilation processes n̄ p → 2 π+ π-, n̄ p → 2 π+ π- π0, and n̄ p → 2 π+ π- 2 π0. The results have been published in Physical Review Letters (Phys. Rev. Lett. 137, 031902 (2026)).
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  Collaboration Meeting in Summer 2026, Jul. 8 - 12, 2026, Yantai University (Yantai, China) The BESIII 2026 Summer Collaboration Meeting was hosted by Yantai University and held at Crowne Plaza Yantai Sea View, Yantai, Shandong Province, China.
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  BESIII Observes Polarization and Measures Electric and Magnetic Moments of the Ξ(1530)⁰ Baryon for the First Time The BESIII Collaboration has achieved a major advance in the study of baryon structure by observing the polarization of the spin-3/2 hyperon Ξ(1530)⁰ and determining its electric and magnetic moments for the first time. The result has been published in Physical Review Letters [Phys. Rev. Lett. 137, 011901 (2026)].
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  Precise test of CP violation in neutral Λ decays The BESIII Collaboration has reported the most precise test to date of CP symmetry in the neutral decays of the Λ hyperon. The result has been published in Physical Review Letters [Phys. Rev. Lett. 136, 251802 (2026)].