Study of the nature of $ι/η(1440)$ in the chiral perturbation theory approach

Abstract

The nature of $ι/η(1440)$ is analysed in the framework of the hypothesis that it represents a single pseudoscalar resonance. Assuming that it arises due to the mixing between the glueball and the $q\bar q$ nearby states ($η$, $η'$, and their radial excitations) two upper estimates are obtained for the partial width $Γ(ι/η(1440) \to K^* K)$ --- one for the case when $ι/η(1440)$ is mainly a glueball and another one when it is mainly a radial excitation of the $s\bar s$ state. Both estimates are obtained in the chiral perturbation theory approach taking into account the available data on the vector mesons and the pseudoscalar state K(1460), which is interpreted as a radial excitation of the $K$ meson. The same partial width is independently estimated on the basis of the combined OBELIX and Crystal Barrel data on the production of $ι/η(1440)$ in $p\bar p$ annihilation. Comparing the results we show that the glueball content of $ι/η(1440)$ is suppressed while its $s\bar s$ radial-excitation interpretation is favoured by the data.