Bounding W-W' mixing with spin asymmetries at RHIC.

The W boson can obtain a small right-handed coupling to quarks and leptons through mixing with a hypothetical W^{'} boson that appears in many extensions of the standard model. Measuring or even bounding this coupling to the light quarks is very challenging. Only one model independent bound on the absolute value of the complex mixing parameter has been obtained to date. Here we discuss a method sensitive to both the real and CP-violating imaginary parts of the coupling, independent of assumptions on the new physics, and demonstrate quantitatively the feasibility of its measurement at RHIC.