Speaker
Description
Light mesons tend to cluster near certain values of mass. It is interesting to notice that such a degeneracy can be described using dynamical $O(4)$-symmetry, like in the hydrogen atom. The meson mass spectrum can be well approximated by linear Regge trajectories of the kind $M^2=a l+b n_r+c$, where $l$ and $n_r$ are angular momentum and radial quantum number, and $a$, $b$, $c$ are coefficients. Such a spectrum arises naturally within the hadron string models. Using 2024 data from the Particle Data Group, a fit for $M^2(l,n_r)$ was performed. Our analysis seems to confirm that $a\approx b$ in the light non-strange mesons, i.e., their masses depend on the sum $l+n_r$ as prescribed by the hydrogen-like $O(4)$-symmetry. Using the semiclassical approximation, we discuss which kind of hadron string models are more favored by the experimental data.
