ProbingCPviolation inγγ→W+W−with polarized photon beams

We demonstrate in a general framework that polarized photons by backscattered laser beams of adjustable frequencies at a TeV linear $e^{+}{e}^{-}$ collider provide us with a very efficient mechanism to probe $\mathrm{CP}$ violation in two-photon collisions. $\mathrm{CP}$ violation in the process $\gamma \gamma \to W^{+}{W}^{-}$ is investigated in detail with linearly polarized photon beams. There are two useful $\mathrm{CP}$-odd asymmetries that do not require detailed information on $W$ decay products. The sensitivity to the $\mathrm{CP}$-odd form factors are studied quantitatively by assuming a perfect $e-\gamma$ conversion and the 20 ${\mathrm{fb}}^{-1\mathrm{}}$ $e^{+}{e}^{-}$ integrated luminosity at the $e^{+}{e}^{-}$ c.m. energies $\sqrt{s}=0.5\mathrm{} \mathrm{and} 1.0$ TeV. The sensitivity is so high that such experiments will allow us to probe new $\mathrm{CP}$ violation effects beyond the limits from some specific models with reasonable physics assumptions. We find that a counting experiment of $W^{+}{W}^{-}$ events in the two-photon mode with adjustable laser frequencies can have much stronger sensitivity to the $\mathrm{CP}$-odd $\gamma \left(\gamma \right)WW$ form factors than can a $W^{+}{W}^{-}$ decay-correlation experiment with a perfect detector achieve in the $e^{+}{e}^{-}$ mode.