Observation of a00(980)−f0(980

Abstract

We report the first observation of a_{0}^{0}(980)-f_{0}(980) mixing in the decays of J/ψ→ϕf_{0}(980)→ϕa_{0}^{0}(980)→ϕηπ^{0} and χ_{c1}→a_{0}^{0}(980)π^{0}→f_{0}(980)π^{0}→π^{+}π^{-}π^{0}, using data samples of 1.31×10^{9} J/ψ events and 4.48×10^{8} ψ(3686) events accumulated with the BESIII detector. The signals of f_{0}(980)→a_{0}^{0}(980) and a_{0}^{0}(980)→f_{0}(980) mixing are observed at levels of statistical significance of 7.4σ and 5.5σ, respectively. The corresponding branching fractions and mixing intensities are measured and the constraint regions on the coupling constants, g_{a_{0}K^{+}K^{-}} and g_{f_{0}K^{+}K^{-}}, are estimated. The results improve the understanding of the nature of a_{0}^{0}(980) and f_{0}(980).

Internal particle width effects on the triangle singularity mechanism in the study of the η(1405) and η(1475) puzzle

“…Thus, other mechanism is required to compensate such a significant deficit. It is also interesting to note that the a 0 ð980Þ − f 0 ð980Þ mixing measured in J=ψ → ϕηπ and χ c1 → 3π at BESIII is at the order of 1% [57], which is consistent with the theoretical prediction of Refs. [58,59] and can be regarded as a direct evidence for additional mechanism that strongly enhances the isospin breakings in η 00 → f 0 ð980Þπ → 3π.…”

Triangle singularities in J/ψ→ηπ0ϕ and π0π0Jing1, Sakai2, Guo3 et al. 2019Phys. Rev. D16210View full textAdd to dashboardCite

“…The BESIII Collaboration reported the Dalitz plot distribution for the decay J=ψ → ηπ 0 ϕ in the ðm 2 ηπ 0 ; m 2 π 0 ϕ Þ plane [2]. Here, let us discuss the triangle singularity contribution to the Dalitz plot.…”

“…1 in Ref. [2]), it is clear that there is a peak near the KK threshold on the ηπ 0 distribution which can be interpreted as the a 0 ð980Þ 0 − f 0 ð980Þ mixing. In addition, there is also a clear accumulation of events for the π 0 ϕ invariant mass being around 1.4 GeV, which would be a peak if the Dalitz plot is projected to the π 0 ϕ invariant mass distribution.…”

“…The BESIII Collaboration reported observations of the a 0 ð980Þ 0 − f 0 ð980Þ mixing in the processes J=ψ → ϕf 0 ð980Þ → ϕa 0 ð980Þ 0 → ϕπ 0 η and χ c1 → a 0 ð980Þ 0 π 0 → f 0 ð980Þπ 0 → π þ π − π 0 [1,2]. The isospin of the a 0 ð980Þ 0 is 1 and that of the f 0 ð980Þ is 0, and, thus, their mixing breaks isospin.…”

Study of the isospin breaking decay Y(2175)→ϕf0(980)Cheng1, Li2, Wang3 et al. 2019Phys. Rev. D8030View full textAdd to dashboardCite

“…Its mixing intensity has been studied extensively on its different aspects and possible manifestations in various processes [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Recently, BESIII Collaboration has reported the first observation of f 0 (980) − a 0 0 (980) mixing in the decays of J/ψ → φf 0 (980) → φa 0 0 (980) → φηπ 0 and χ c1 → a 0 0 (980)π 0 → f 0 (980)π 0 → π + π − π 0 [31]. In their work, the values of the mixing intensity ξ f a for the f 0 (980) − a 0 0 (980) transition was obtained ξ f a = (0.99 ± 0.35) × 10 −2 (solution-1) , ξ f a = (0.41 ± 0.25) × 10 −2 (solution-2) .…”