An overview of η and η′ decays at BESIII

Abstract

The world's largest sample of 1.31 billion J/ψ events accumulated at the BESIII detector, provides a unique opportunity to investigate η and η ′ physics via two body J/ψ radiative or hadronic decays. For many η ′ decay channels the low background data samples are up to three orders of magnitude larger than collected in any previous experiment. Here we review the most significant results on η and η ′ obtained at BESIII so far. The analyses range from detailed studies of the common decays dynamics, observations of new radiative and Dalitz decays, and search for rare/forbidden decays with sensitivity up to B ∼ 10 −5 . Finally, prospects of the forthcoming runs at J/ψ peak for the η and η ′ physics are discussed.

Radiative corrections to the η(′) Dalitz decays

“…As it was in the pion case, radiative corrections for these processes are crucial in order to extract relevant information from the data. This goes together with the fact that currently an ambitious experimental η (′) program aiming for an accuracy never reached before is running, for instance, at experiments BES-III [8], A2 [9] or GlueX [10]. Note that in [1] and also throughout the present work we study fully inclusive radiative corrections, i.e.…”

η′ and η mesons with connection to anomalous glue

“…The large branching ratios for this decay tell us that non-leading terms play a vital role. We refer to the lectures of Kupsc (2009) for further details of the analysis of these processes and to Fang et al (2018) for a review of the latest experimental results from the BES experiment, as well as earlier measurements of these decays.…”

Scouring meson decays for true muonium

“…and is proportional to Fγ * γ * (z1, z2) next decade [46]. This 10 10 J/ψ is right at the edge of what is necessary for an inclusive search.…”