Status of the Jefferson Lab Eta Factory (JEF) experiment*

The Jefferson Lab Eta Factory (JEF) experiment will leverage an upgraded GlueX

detector in Hall D at  Jefferson Lab to use the production and subsequent decays

of η mesons to determine the u/d quark mass ratio, to set constraints on

new C-violating/P-conserving reactions, and to search for signatures of Beyond

Standard Model physics.  In particular, the η→π⁰γγ channel

can be used to provide a window into chiral perturbation theory at

O(p⁶) and to search for lepto-phobic dark vector (B) bosons in

the reaction η→Bγ (B→π⁰γ) or dark scalar (S) bosons

in the reaction η→π⁰S (S→γγ).  This channel requires

replacing the inner region of the Forward Calorimeter (FCAL) of the GlueX

detector with an array of 40×40 lead tungstate modules that will

provide a factor of two improvement in position and energy resolution

relative to the existing blocks.

This talk will summarize the experimental program and present the status of the

FCAL upgrade.