Future colliders

I review initiatives for future lepton hadron colliders being pursued by the particle and nuclear physics communities in the US. The first one is the eRHIC at Brookhaven National Laboratory (BNL), which will require construction of a high intensity, polarized electron beam facility next to the Relativistic Heavy Ion Collider (RHIC) complex that is just becoming fully functional. It will also need modification of the hadron rings, but these changes will disrupt neither the heavy ion physics nor the RHIC spin program that has just started, both of which are expected to continue into early in the next decade. The second option recently being considered is the construction of a hadron ring next to the existing CEBAF electron beam facility at the Jefferson Laboratory. While severe physical and geographical constraints exist for this proposal, the use of futuristic technology in the project may allow polarized electron light ion collisions at unusually high luminosities. It is hoped that at least one of these proposals will eventually be built.