Exclusive production of \chi_{c}(0^{+}) meson and its measurement in the   \pi^{+}\pi^{-} channel
  We report on the results of a theoretical study of the central exclusive production of scalar $\chi_{c}(0^{+})$ meson via $\chi_{c0} \to \pi^{+}\pi^{-}$ decay in high-energy hadron collisions at the RHIC, Tevatron and LHC. The corresponding amplitude for exclusive double-diffractive $\chi_{c0}$ meson production was obtained within the $k_{t}$-factorization approach including virtualities of active gluons and the cross section is calculated with unintegrated gluon distribution functions (UGDFs) known from the literature. The four-body $p p \to p p \pi^+ \pi^-$ reaction constitutes an irreducible background to the exclusive $\chi_{c0}$ meson production. We include the absorption effects due to proton-proton interaction and pion-pion rescattering. Several differential distributions for $pp(\bar{p}) \to pp(\bar{p})\chi_{c0}$ process, including the absorptive corrections, were calculated. The influence of kinematical cuts on the signal-to-background ratio is investigated. 
Piotr Lebiedowicz, Roman Pasechnik, Antoni Szczurek
hep-ph