Diffractive pQCD mechanism of exclusive production of $W^+ W^-$ pairs in   proton-proton collisions
  We present a study of central exclusive production of $W^+W^-$ pairs in proton-proton collisions at the LHC. We compare the contribution of the $\gamma \gamma \to W^+ W^-$ mechanism with a new mechanism of exclusive diffractive production through the $gg \to W^+ W^-$ subprocess with intermediate virtual Higgs boson and quark box diagrams. The amplitude for the latter process is expressed in terms of the off-diagonal unintegrated gluon distribution functions. Several observables related to this process are calculated. The phase space integrated diffractive contribution when separated is only a small fraction of fb compared to 115.4 fb of the $\gamma\gamma$-contribution without absorption. This opens a possibility of efficient searches for anomalous boson $\gamma W^+ W^-$ and $\gamma \gamma W^+ W^-$ couplings due to new physics beyond Standard Model. 
Piotr Lebiedowicz, Roman Pasechnik and Antoni Szczurek
hep-ph