Exclusive diffractive production of $π^{+}π^{-}π^{+}π^{-}$ via the intermediate $σσ$ and $ρρ$ 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 $pp \to pp π^{+} π^{-} π^{+} π^{-}$ 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 $σσ$ and $ρρ$ contributions to the $π^{+} π^{-} π^{+} π^{-}$ 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 $ρρ$ contribution which is treated here for the first time. The mechanism considered gives a significant contribution to the $pp \to pp π^{+} π^{-} π^{+} π^{-}$ 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 $μb$ 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.

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