η ...? Why η ?

• Goal (1): Compare high pT production for a new hadron species (η) in 3 systs:

• p+p (“QCD vacuum”), d+Au (“cold QCD medium”), Au+Au (“hot QCD medium”)

• Goal (2): Have under control the 2nd largest hadronic source (η) of decay photon bckgd for direct g and “direct” e± studies.