Ablikim, M.Achasov, M. N.Ahmed, S.Ai, X. C.Albayrak, O.Albrecht, M.Ambrose, D. J.Lou, XinchouBESIII Collaboration2018-10-012018-10-012017-12-072018-10-012470-0010http://hdl.handle.net/10735.1/6174Includes supplementary materialThe decays of χ(c2) → K⁺K⁻ π⁰, K(S)K(±)π(∓), and π⁺π⁻π⁰ are studied with the ψ(3686) data samples collected with the Beijing Spectrometer ( BESIII). For the first time, the branching fractions of χ(c2) → K*K̅, χ(c2) → a₂(±)(1320)π(∓)/a₂⁰(1320)π⁰, and χ(c2) → ρ(770)(±)π(∓) are measured. Here, K*K̅ denotes both K*(±)K(∓) and its isospin-conjugated process K*⁰K̅⁰ + c.c., and K* denotes the resonances K*(892), K₂*(1430), and K₃*(1780). The observations indicate a strong violation of the helicity selection rule in χ(c2) decays into vector and pseudoscalar meson pairs. The measured branching fractions of χ(c2) → K*(892)K̅ are more than ten times larger than the upper limit of χ(c2) → ρ(770)(±)π(∓), which is so far the first direct observation of a significant U-spin symmetry breaking effect in charmonium decays.en©2017 American Physical Society. All Rights Reserved.MesonsIsobaric spinBranching fractions (Nuclear physics)CharmoniumarticleAblikim, M., M. N. Achasov, S. Ahmed, X. C. Ai, et al. 2017. "Observation of the helicity-selection-rule suppressed decay of the χ(c2) charmonium state." Physical Review D 96(11), doi:10.1103/PhysRevD.96.1111029611