Narrow Results

In this work, the mixing angle of the vector $\omega (782)$ and $\varphi (1020)$ mesons is estimated in the framework of Nambu–Jona-Lasinio model. The decay $\varphi \to {\pi }^0\gamma$ is considered as a basic process to determine this angle. The obtained value is compared with the results of the other authors. Besides, the width of the decay $\varphi \to 3\pi$ and the cross-section of the process $e^{+}{e}^{-}\to {\pi }^0\varphi$ are calculated by using this angle.

We discuss the influence of external magnetic field on strong decays of $K^{\ast }(892)$, $\varphi (1020)$ and ${\rho }^0(770)$ mesons. Due to increasing energy of $n=0$ Landau level of charged decay products, particular decay channels may become suppressed and isospin rules for strong decays can be violated. In the case of ${\rho }^0$ meson, enhanced production of photons and dileptons (with modified invariant mass) may occur. Similar considerations are applied to decays of ${\mathrm{\Xi }}^{\ast }(1530)$ baryon. We also suggest that static electromagnetic field of sufficient strength can modify the internal structure (wavefunction) of ${\eta }_c,$ J/$\mathrm{\Psi }$ and $\mathrm{{\rm Y}}(ns)$ mesons, and specific decay channels (e.g. CP — violating $\eta \to {\pi }^{+}{\pi }^{-}$) can become enhanced.