Semihadronic and hadronic decays of ${\rho }^0$ and $\omega$ mesons coherently photoproduced in the isoscalar nuclei

Abstract

The interference of the ${\rho }^0$ and $\omega$ mesons has been studied in the hadronic and leptonic decay channels, i.e., dipion and dilepton decay channels respectively, but this interference is not studied yet in the semihadronic or semileptonic decay channel, e.g., $V\to {\pi }^0\gamma$. $V$ denotes either ${\rho }^0$ or $\omega$ meson. To look for the quoted interference in the ${\pi }^0\gamma$ decay channel as well as the contribution of $\rho$ meson to the cross section, the correlated ${\pi }^0\gamma$ invariant mass distribution spectra are calculated in the photonuclear reaction in the multi-GeV region. It is assumed that these bosons arise in the final state due to the decay of ${\rho }^0$ and $\omega$ mesons which are photoproduced coherently in the isoscalar nucleus. The elementary reaction in the nucleus is considered to proceed as $\gamma N\to VN$; $V\to {\pi }^0\gamma$. The forward propagation of the $\rho$ and $\omega$ mesons and the near forward emission of pion are considered, so that they can be described by the eikonal form. The meson nucleus interactions are evaluated using $t\varrho$ approximation. Replacing the decay vertex $V\to {\pi }^0\gamma$ by $V\to {\pi }^{+}{\pi }^{-}$ in the above formalism, it is also used to study the $\rho -\omega$ interference in the ${\pi }^{+}{\pi }^{-}$ decay channel.

Comments: 17 pages, 5 figures