χc decays and the gluon component of the η′, η mesons

Abstract

The large mass of the η′ meson indicates that a sizeable gluon component is present in the meson wave function. However, the χc0 and χc2 decays to η′ mesons, which proceed via a purely gluonic intermediate state and we would therefore naïvely expect to be enhanced by such a component, are in fact relatively suppressed. We argue that this apparent contradiction may be resolved by a proper treatment of interference effects in the decay. In particular, by accounting for the destructive interference between the quark and gluon components of the η′ distribution function, in combination with a model for strange quark mass effects, we demonstrate that the observed χc(0,2)→η(′)η(′) branching ratios can be reproduced for a reasonable gluon component of the η′, η mesons.