Exclusive scalar [formula omitted] meson production for energy ranges available at the GSI Facility for Antiproton and Ion Research (GSI-FAIR) and at the Japan Proton Accelerator Research Complex (J-PARC)

Abstract

We evaluate differential distributions for exclusive scalar f 0 ( 1500 ) meson (glueball candidate) production for p p ¯ → N 1 N 2 f 0 (FAIR@GSI) and p p → p p f 0 (J-PARC@Tokai). Both QCD diffractive, pion–pion meson exchange current (MEC) components as well as double-diffractive mechanism with intermediate pionic loop are calculated for the first time in the literature. The pion–pion component, which can be reliably calculated, dominates close to the threshold while the diffractive component may take over only for larger energies. At the moment only upper limit for the QCD-diffractive component can be obtained. The diffractive component is calculated based on two-gluon impact factors as well as in the framework of Khoze–Martin–Ryskin approach proposed for diffractive Higgs boson production. Different unintegrated gluon distribution functions (UGDFs) from the literature are used. Rather large cross sections due to pion–pion fusion are predicted for PANDA energies, where the gluonic mechanism is shown to be negligible. The production of f 0 ( 1500 ) close to threshold could limit the so-called πNN form factor in the region of larger pion virtualities. We discuss in detail the two-pion background to the production of the f 0 ( 1500 ) meson.