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 ${\eta }^{\prime }$, 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 $\eta$.

Comments: 8 pages, 3 figures, contribution to ICHEP04, Beijing, 2004