Status of the η′ (957) Meson

Abstract

A b s t r a c t . According to the quark model, a singlet with I G J p = o+ois predicted to exist.Expcrinientally observed, the q'(95i) and t,he E(1420) mesons both have the same properties. Howw c r , the J p the 71' meson may be 0-or 2-. Recent experimental results along with some theoretiml disrrissions on the production nnd the decay of the $meson are presented here. Its main decay modes are zzq, z + x -~ (via e'y) and jy. Zastnnd des 7' (957) Mesons l n h n l t s u b e r s i c h t . GemiiB dem Quark-Mode11 wird ein Singuiett mit I G J p = 0+0voraiisgesagt. \Vie bereits experimentell beobachtet ist, besitzen die ~'(957)-und E(1420)-Yesonen dieselben Eigeiwcliaften. Jedocli konnten die Jp-\Vcrte des q'(957)-Mesons 0-oder 2sein. Im folgenden betmchten wir einige nenere experimentelle Ergebnisse, zusammen mit theoretisrhen Vberlegiingen zur Erzcrigung rind Zuni Zerfall des q'Jfesons, mit den hauptsiiehliehen Zerfallskanitlen: nnq, n+.-r-y (via coy) rind jy. Status of the ~'(967) Meson 3 SU(3) Properties in Tcrms of QuarkThe SU(3) may be assumed to be made up of quarks and the properties of multiplets can be derived. The hypothesis of quark was put forward by GELL-MANN and ZWEIG.According to them, there is a basic triplet ql, q2. and q3 of quarks consisting of an isospin singlet, q3. The properties of quarks are given in Table 1. The quarks q are denoted by and antiquarks gbya-