Hunting for contact interactions at HERA with polarized lepton and proton beams

We explore the discovery and analysis potentials of the HERA collider, with and without polarized beams, searching for electron-quark contact interactions in the neutral current channel. We find that the sensitivity to contact interactions when both beams are polarized is similar to the unpolarized case, and is better than in the case where one has only lepton polarization. We emphasize that the measurement of spin asymmetries in such a polarized context could give some crucial information on the chiral structure of these postulated new interactions. The experimental conditions are carefully taken into account.