New physics signatures at a linear collider: model-independent analysis from ‘conventional’ polarized observables

We discuss four-fermion contact-interaction searches in the processes e+e−→μ+μ−, cc̄ and bb̄ at a future e+e− linear collider with c.m. energy s=0.5 TeV and with both beams longitudinally polarized. Our analysis is based on the measurements of familiar polarized observables such as the total cross section and the forward–backward/left–right asymmetries, and accounts for the general set of contact interaction couplings as independent, nonzero, parameters thus avoiding simplifying, model-dependent, assumptions. We derive the corresponding model-independent constraints on the above-mentioned coupling constants, and evaluate the corresponding reach at the linear collider, emphasizing the role of beam polarization. We compare the results with a model-dependent procedure where only one coupling is varied at a time.