Radial excitations of mesons and nucleons from QCD sum rules

Abstract

Within the framework of QCD sum rules, we use the least-squares fitting method to investigate the first radial excitations of the nucleon and light mesons such as $\ensuremath{\rho}$, ${K}^{*}$, $\ensuremath{\pi}$, and $\ensuremath{\varphi}$. The extracted masses of these radial excitations are consistent with the experimental data. In particular, we find that the decay constant of $\ensuremath{\pi}(1300)$, which is the first radial excitation of $\ensuremath{\pi}$, is tiny and is strongly suppressed as a consequence of chiral symmetry.