Probing triple gauge couplings with transverse beam polarisation in $e^ + e^- \rightarrow W^ + W^-$

The prospects of measuring triple gauge couplings in W pair production at future linear colliders with transverse beam polarisation are studied. We consider CP conserving and CP violating couplings with both real and imaginary parts. The maximum achievable sensitivity in a simultaneous measurement of all couplings is determined using optimal observables, extending an earlier analysis for longitudinal beam polarisation. We find good sensitivity to the coupling Im$(g^{R}_{1} + \kappa{_R})$, which is not measurable with longitudinal polarisation. In contrast, for the real parts (including the CP violating couplings) the sensitivity is better if both beams are longitudinally polarised. We conclude that a comprehensive measurement of all triple gauge couplings requires both transverse and longitudinal beam polarisation