HERA+LC-BASED γp COLLIDER: LUMINOSITY AND PHYSICS

We discuss the possibility of constructing a linac ring type ep collider and a γp collider based on it at DESY, namely the HERA+LC proposal. Using the parameters of the proton ring of HERA and those of the proposed linear e+e− collider (LC), we expect a luminosity of Lγp=1–2×1031 cm−2s−1, due to reasonable improvement of the proton beam. In a γp collider, the high energy γ beam is produced by the Compton backscattering of laser photons off the electron beam from the linear accelerator. In the case of the opposite choice of laser photon and electron beam helicities, the luminosity of γp collisions still exceeds 1031 cm−2s−1 up to a distance of 12 m between the conversion region and the collision point. We examine the physics research program for the HERA+LC γp collider proposal. The search for supersymmetric partners, leptoquark production and heavy quark investigations are considered in detail. The capacity of HERA+LC surpasses that of HERA and is comparable with the LC. Polarization facilities of the gamma and proton beams, and the clearer background compared to the hadron colliders, are stated as additional advantages of the proposed γp collider.