Contact interaction probes at the Linear Collider with polarized electron and positron beams

For contact-interaction searches at the Linear Collider, we discuss the advantages of polarizing both the electron and the positron beams as compared with polarizing only the electron beam. In particular, for the processes ee → μμ, ττ, bb̄ and cc̄ at a future ee collider with √ s = 0.5 TeV we derive model-independent bounds on the four-fermion contact interaction parameters from studies of the helicity cross sections. Partially supported by the Research Council of Norway, and by MURST (Italian Ministry of University, Scientific Research and Technology).