The Experimental Programs on Light Pseudoscalar Meson Decays

The decays of the low-lying pseudoscalar mesons (π⁰, η, and η′) allow access to a plethora of physics probes, from

measurements of fundamental properties of matter such as the up-down quark

mass ratio, to studies of channels that access higher-order terms in Chiral

Perturbation

theory, to tests of fundamental symmetries and searches for signatures of

physics beyond the Standard Model. Several experiments have studied pseudoscalar

decays: these experiments include PrimEx in Hall B at Jefferson Lab, A2 at the

MAMI electron accelerator facility,

the KLOE-II experiment at the DAΦNE φ-factory, WASA-at-COSY at the

cooler synchrotron COSY storage ring,

and BESIII at the Beijing charm factory. In Hall D at Jefferson Lab, PrimEx-eta uses the Primakoff process

to measure the η radiative width using the GlueX spectrometer.

In the near future the Jefferson Lab Eta Factory (JEF) experiment will use the

GlueX spectrometer with an upgraded forward calorimeter to study η(′)

decay channels with a focus on all-neutral final states. Finally, a proposal

for a new experiment, ``Rare Eta Decays with a TPC for Optical Photons''

(REDTOP) utilizing a proton beam on fixed targets, is under development.

Highlights from previous and ongoing experiments and plans for future experiments will be presented.