Speaker
Description
Precision measurements of several η(′) decay channels, with emphasis on rare neutral modes, will be carried out at the Jefferson Lab Eta Factory (JEF). This experiment will employ the baseline GlueX detector at Hall D/Jefferson Lab, augmented by upgrading the central region of the electromagnetic, Forward CALorimeter (FCAL-II) and is scheduled to run in 2023-4. Copious numbers of forward-boosted η(′) mesons will be produced through the γ + p → η(′) + p reaction, using an 8-12 GeV tagged photon beam. The reaction decay particles will be measured with a high-resolution PbWO4 crystal insert in the FCAL central region that minimizes shower overlaps and optimizes the resolutions of energy and position. The combination of highly boosted eta/eta' production, recoil proton detection, and PWO insert makes JEF unique compared to other eta/eta' experiments.The JEF physics program will allow a search for new gauge bosons in portals coupling the SM sector to the dark sector in the invariant mass region below 1 GeV: a leptophobic vector boson which couples to baryon number will be sought via the π0γγ and π+π-π0 channels; a dark photon or leptophilic vector bosons could be accessible via π0e+e-; and the presence of a hadrophilic scalar and axion-like particles that couple to photons will also be probed. The rich JEF physics also includes C-violating eta(‘) decays, constraints on C-violating, P-conserving reactions, precision tests of low energy QCD [O(p6) ChPT] and Dalitz analyses to access the quark mass ratio. Details of the physics goals and an update on the experimental hardware will be presented.
