Exclusive diffractive production of $\pi^{+}\pi^{-}\pi^{+}\pi^{-}$ via the intermediate $\sigma\sigma$ and $\rho\rho$ states in proton-proton collisions within tensor pomeron approach
We present first predictions of the cross sections and differential distributions for the central exclusive reaction $pp \to pp \pi^{+} \pi^{-} \pi^{+} \pi^{-}$ being studied at RHIC and LHC. The amplitudes for the processes are formulated in terms of the tensor pomeron and tensor $f_{2 R}$ reggeon exchanges with the vertices respecting the standard crossing and charge-conjugation relations of Quantum Field Theory. The $\sigma \sigma$ and $\rho \rho$ contributions to the $\pi^{+} \pi^{-} \pi^{+} \pi^{-}$ final state are considered focussing on their specificities. The correct inclusion of the pomeron spin structure seems crucial for the considered sequential mechanisms in particular for the $\rho\rho$ contribution which is treated here for the first time. The mechanism considered gives a significant contribution to the $pp \to pp \pi^{+} \pi^{-} \pi^{+} \pi^{-}$ reaction. We adjust parameters of our model to the CERN-ISR experimental data and present several predictions for the STAR, ALICE, ATLAS and CMS experiments. A measurable cross section of order of a few $\mu b$ is obtained including the experimental cuts relevant for the LHC experiments. We show the influence of the experimental cuts on the integrated cross section and on various differential distributions.