The Glueball Candidate \eta(1440) as \eta Radial Excitation

Abstract

The Particle Data Group decided to split the $\eta(1440)$ into two states, called $\eta_L$ and $\eta_H$. The $\eta(1295)$ and the $\eta_H$ are supposed to be the radial excitations of the $\eta$ and $\eta'$, respectively. The $\eta_L$ state cannot be accomodated in a quark model; it cannot be a $q\bar q$ state, however, it might be a glueball. In this contribution it is shown that that the $\eta(1295)$ does not have the properties which must be expected for a radially excited state. The splitting of the $\eta(1440)$ is traced to a node in the wave function of a radial excitation. Hence the two peaks, $\eta_L$ and $\eta_H$, originate from one resonance which is interpreted here as first radial excitation of the $\eta$.