Amplitude analysis of the χc1→ηπ+π− decays

Abstract

Using 448.0 × 10 6 ψ(3686) events collected with the BESIII detector, an amplitude analysis is performed for ψ(3686) → γχc1, χc1 → ηπ + π − decays. The most dominant two-body structure observed is a0 (980) ± π ∓ ; a0(980) ± → ηπ ± . The a0(980) line shape is modeled using a dispersion relation, and a significant non-zero a0(980) coupling to the η ′ π channel is measured. We observe χc1 → a2(1700)π production for the first time, with a significance larger than 17σ. The production of mesons with exotic quantum numbers, J P C = 1 −+ , is investigated, and upper limits for the branching fractions χc1 → π1(1400) ± π ∓ , χc1 → π1(1600) ± π ∓ , and χc1 → π1(2015) ± π ∓ , with subsequent π1(X) ± → ηπ ± decay, are determined.

Observation of the Semileptonic Decay D0→a0(980)−Ablikim1, Ачасов2, Ahmed3 et al. 2018Phys. Rev. Lett.Self Cite371170View full textAdd to dashboardCite

“…The signal shape in the U distribution is described by the MC simulation and that in the M ηπ distribution is modeled with a usual Flatté formula [24] for the a 0 ð980Þ signal. The mass and two coupling constants g 2 ηπ and g 2 KK are fixed to 0.990 GeV=c 2 , 0.341 ðGeV=c 2 Þ 2 , and 0.304 ðGeV=c 2 Þ 2 [25], respectively. The backgrounds are divided into three classes: the residual background from semileptonic D → ρ; K 0 S and K Ã decays mentioned previously (bkg I), the partially reconstructed hadronic D decays (bkg II), and the non-DD background (bkg III).…”

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

“…here, the minus sign is associated with the λ π 0 η vertex corresponding to the π 0 ↔ η transition [13,46,47]. m f 0 = (0.99 ± 0.02)GeV [44] Γ f 0 = 0.074GeV [48] m a 0 = (0.98 ± 0.02)GeV [44] Γ a 0 = (0.092 ± 0.008)GeV [44] m Y = (2.188 ± 0.010)GeV [44] Γ Y = (0.083 ± 0.012)GeV [44] m φ = 1019M eV [44] g a 0 ηπ 0 = 2.43GeV [1,49] g a 0 K + K − = (2.76 ± 0.46)GeV [50,51] g a 0 K 0K0 = (2.76 ± 0.46)GeV [50,51] g f 0 π + π − = 1.39GeV [1,49] g f 0 π 0 π 0 = 0.98GeV [1,49] [29] where Γ f 0 and Γ a 0 are the decay widths of f 0 (980) and a 0 0 (980), respectively. From Refs.…”

Visible narrow cusp structure in Λc+→pK−π+ enhanced by triangle singularity

“…There are also some other less prominent cusps observed in experiments, such as the one in γp → π 0 p at the π + n threshold [8]. In recent years, the cusp phenomena have ever been introduced to describe some resonance-like structures in both the heavy hadron [9][10][11] and light hadron sectors [12][13][14][15][16][17][18][19][20][21][22]. But it should be warned that depending on the coupling strength to the open threshold, not all cusp effects would pro- * Electronic address: xiaohai.liu@tju.edu.cn † Electronic address: gli@qfnu.edu.cn ‡ Electronic address: xiejujun@impcas.ac.cn § Electronic address: zhaoq@ihep.ac.cn duce predominant resonance-like enhancements [23].…”