Neutral decays ofη′(958)

Theoretical analysis of the doubly radiative decays η(′)→π0γγ and Escribano1, Gonzàlez-Solís2, Jora3 et al. 2020Phys. Rev. D

“…For the η 0 → π 0 γγ decay, the BESIII Collaboration has recently reported for the first time the associated m 2 γγ invariant mass distribution [10]. The measured branching fraction is BR ¼ ð3.20 AE 0.07 AE 0.23Þ × 10 −3 , superseding the upper limit BR < 8 × 10 −4 at 90% CL determined by the GAMS-2000 experiment [24]. Finally, for the η 0 → ηγγ decay, a measurement of BR < 1.33 × 10 −4 at 90% CL has been provided, again for the first time, by the BESIII Collaboration [11].…”

“…1(a)], and consequently its integrated decay width might be linked to a normalization problem associated to the parameter g in Eqs. (11) and (24). One could argue, though, that this parameter is fixed by the VPγ experimental data, which is measured nowadays to a high degree of accuracy and leads to satisfactory predictions for the other two processes, i.e., η 0 → π 0 γγ and η 0 → ηγγ, and, therefore, should not be changed.…”

Amplitude Analysis of the Decays η′→π+π−πAblikim1, Ачасов2, Ai3 et al. 2017Phys. Rev. Lett.330170View full textAdd to dashboardCite

“…Recently the decay was also observed by the BESIII experiment [9] with a branching fraction consistent with the CLEO-c result; however, no Dalitz plot analysis was presented. Interest in the decay channel η 0 → π 0 π 0 π 0 stems from the observed 4σ discrepancy between the recent branching fraction measurement by BESIII [ð35.6 AE 4.0Þ × 10 −4 ] [9] and those from all previous experiments [10][11][12]. The BESIII result indicates a value for the ratio r 0 that is two times larger than previous experiments.…”

Prospects for e+e- physics at Frascati between the φ and the ψ

“…A recent full p 4 ChPT calculation with higher order resummation via Bethe-Salpeter equations has been performed to precisely predict the dynamics of these decays [114]. The best experimental results currently available come from GAMS [115] for the π 0 π 0 η mode (about 6000 events) and from the VES collaboration for the π + π − η mode [116]. The latter have been obtained with about 20 thousands events in hadronic production (diffractive + charge exchange).…”