Measurement of the matrix elements for the decaysη→π+π−π0and

Abstract

Measurement of the matrix elements for the decays η→π^{+}π^{-}π^{0} and η/η^{′}→π^{0}π^{0}π^{0}Phys. Rev. D 92, 012014

η′ and η mesons with connection to anomalous glue

“…Recent accurate measurements of the η decay to charged pions, η → π + π − π 0 , have been performed by the WASA-at-COSY experiment at FZ-Jülich (Adlarson et al, 2014b), the KLOE-2 Collaboration at LN-Frascati (Anastasi et al, 2016) and at BES in Beijing (Ablikim et al, 2017). The neutral 3 pion decay η → 3π 0 has most recently been measured by WASA (Adolph et al, 2009), KLOE (Ambrosino et al, 2011), the Mainz A2 Collaboration (Prakhov et al, 2018) and at BES (Ablikim et al, 2015a).…”

Amplitude Analysis of the Decays η′→π+π−πAblikim1, Ачасов2, Ai3 et al. 2017Phys. Rev. Lett.Self Cite340170View full textAdd to dashboardCite

“…The significant resonant Swave contribution also provides a reasonable explanation for the negative slope parameter of the η 0 → π 0 π 0 π 0 Dalitz plot [13]. The ratio of the branching fractions between the S-wave components Bðη 0 → π 0 π 0 π 0 Þ=Bðη 0 → π þ π − π 0 Þ S is determined to be 0.94 AE 0.03 AE 0.13, where the common systematic uncertainties cancel out.…”

“…The BESIII result indicates a value for the ratio r 0 that is two times larger than previous experiments. Furthermore, the recent determination of the Dalitz plot slope parameter for η 0 → π 0 π 0 π 0 decay gave α ¼ −0.687 AE 0.061 [13], which deviates significantly from that for the phase-space distribution (α ¼ 0). This implies that final-state interactions play an essential role.…”

“…The selection criteria for charged tracks and photon candidates are the same as those in Ref. [13]. Because the radiative photon from the J=ψ is always more energetic than the photons from the π 0 decays, the photon candidate with the maximum energy in the event is taken as the radiative one.…”

Search for hc→π+π−J/ψ<

“…The angular distribution of the η is modeled as 1 þ cos 2 θ η , where θ η is the angle between η momentum and the positron beam in the rest frame of ψð3686Þ. The decay η → π 0 π þ π − is generated by EvtGen [20] with the measured Dalitz plot amplitude [23], and π 0 → γγ by a phase space distribution. The J=ψ decays to l þ l − are generated with an angular distribution of 1 þ cos 2 θ l , where θ l is the angle between the l þ momentum in the J=ψ rest frame and the J=ψ momentum in the ψð3686Þ rest frame.…”