Optimal beam polarizations for new-physics search through γγ → tt̄ → ℓX/bX

Abstract

We perform an optimal-observable analysis of the final charged-lepton/b- quark momentum distributions in γγ→tt̄→ℓX/bX for various beam polarizations in order to study possible anomalous tt̄γ, tbW and γγH couplings, which could be generated by SU(2) × U(1) gauge-invariant dimension-6 effective operators. We find optimal beam polarizations that will minimize the uncertainty in determination of those non-standard couplings. We also compare eē and γγ colliders from the viewpoint of the anomalous-top-quark-coupling determination. © SISSA 2005.