Observation of the helicity-selection-rule suppressed decay of the chi(c2) charmonium state
AuthorKolcu, Onur Buğra
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CitationAblikim, M., Achasov, M. N., Ahmed, S., Ai, X. C., Albayrak, O., Albrecht, M., . . . Collaboration, B. (2017). Observation of the helicity-selection-rule suppressed decay of the chi(c2) charmonium state. Physical Review D, 96(11), 8. doi:10.1103/PhysRevD.96.111102
The decays of chi(c2) -> K+K- pi(0), KSK +/-pi(-/+), and pi(+)pi(-)pi(0) are studied with the psi(3686) data samples collected with the Beijing Spectrometer ( BESIII). For the first time, the branching fractions of chi(c2) -> K*(K) over bar,chi(c2) -> a(2)(+/-)(1320)pi(-/+)/a(2)(0)(1320)pi(0), and chi(c2) -> rho(770)(+/-)pi(-/+) are measured. Here, K*(K) over bar denotes both K*K-+/-(-/+) and its isospin-conjugated process K*(0)(K) over bar (0) + c: c:, and K* denotes the resonances K*(892), K*(2)(1430), and K*(3)(1780). The observations indicate a strong violation of the helicity selection rule in chi(c2) decays into vector and pseudoscalar meson pairs. The measured branching fractions of chi(c2) -> K*(892)(K) over bar are more than ten times larger than the upper limit of chi(c2) -> rho(770)(+/-)pi(-/+), which is so far the first direct observation of a significant U-spin symmetry breaking effect in charmonium decays.