$pp \to pp K^{+}K^{-}$ reaction at high energies

Abstract

We evaluate differential distributions for the four-body $p p \to p p K^{+} K^{-}$ reaction at high energies which constitutes an irreducible background to three-body processes $p p \to p p M$, where $M=\phi$, $f_{2}(1275)$, $f_{0}(1500)$, $f_{2}'(1525)$, $\chi_{c0}$. We consider central diffractive contribution mediated by Pomeron and Reggeon exchanges as well as completely new mechanism of emission of kaons from the proton lines. We include absorption effects due to proton-proton interaction and kaon-kaon rescattering. We compare our results with measured cross sections for the CERN ISR experiment. We make predictions for future experiments at RHIC, Tevatron and LHC. Differential distributions in invariant two-kaon mass, kaon rapidities and transverse momenta of kaons are presented. Two-dimensional distribution in $(y_{K^+}, y_{K^-})$ is particularly interesting. The higher the incident energy, the higher preference for the same-hemisphere emission of kaons. We find that the kaons from the new mechanism of emission directly from proton lines are produced rather forward and backward but the corresponding cross section is rather small. The processes considered here constitute a sizeable contribution to the total proton-proton cross section as well as to kaon inclusive cross section. We consider a measurement of exclusive production of scalar $\chi_{c0}$ meson in the proton-proton collisions via $\chi_{c0} \to K^{+}K^{-}$ decay. The corresponding amplitude for exclusive central diffractive $\chi_{c0}$ meson production is calculated within the $k_{t}$-factorization approach. The influence of kinematical cuts on the signal-to-background ratio is discussed.