Transverse Polarization Signatures of Extra Dimensions at Linear Colliders

Abstract

If significant longitudinal polarization of both the electrons and positrons becomes feasible at a future linear collider(LC), it may be possible to use spin rotators to produce transversely polarized beams. Using the transverse polarization of both beams, new azimuthal spin asymmetries can be formed which will be sensitive probes for new physics beyond the Standard Model. Here we demonstrate that these asymmetries are particularly sensitive to the exchange of Kaluza-Klein towers of gravitons, or other spin-2 fields, that are predicted to exist in higher dimensional theories which address the hierarchy problem. These new asymmetries are shown to be able to extend the search reach for such new physics by more than a factor of two, provide an additional tool for isolating the signatures for spin-2 exchange up to mass scales in excess of $10\sqrt s$, and can be used to help differentiate among the proposed solutions to the hierarchy problem below the production threshold for new particles.