Aspects of Meson Spectroscopy with N̅N Annihilation

Abstract

We focus on the potentialities of nucleon-antinucleon (NN) annihilation as a means of producing new mesonic states. The case for the existence of quasinuclear NN bound states is discussed in detail. Strong evidence for a 2 ++ (0 + ) state of this type has been obtained at LEAR in annihilation from the p-wave (L = 1) NN system, in support of earlier sightings of this object in L -0 annihilation at Brookhaven. In the next generation of LEAR experiments, the emphasis shifts to the search for mesons containing dynamical excitations of the gluonic field, namely glueballs and hybrids (QQg)-We discuss some features of the masses, decay branching ratios and production mechanisms for these states, and suggest particular NN annihilation channels which are optimal for their discovery.