$\omega-\rho$ Mixing and the $\omega\to\pi\pi\gamma$ Decay

We evaluate the width of the $\omega$ meson in nuclear matter. We consider the free decay mode of the $\omega$ into three pions, which is dominated by $\rho \pi$ decay, and replace the $\rho$ and $\pi$ propagators by their medium modified ones. We also take into account the quasielastic and inelastic processes induced by a vector-baryon interaction dominated by vector meson exchange, as well as the contributions coming from the $\omega \to K \bar K$ mechanism with medium modi...

The arguments are put forward that the many pion decays omega ->2 pi^+ 2 pi^- pi^0 and pi^+ pi^- 3 pi^0 provide an ideal test site for testing the predictions of chiral models of the vector meson decays into many pions. Using the approach based on the Weinberg Lagrangian or, in a new language, the Lagrangian of hidden local symmetry added with the term induced by the anomalous Lagrangian of Wess and Zumino, the partial widths of these decays are evaluated, and their excitatio...

In this paper we evaluate sources of background for the $\gamma p \to \omega p$, with the $\omega$ detected through its $\pi^0 \gamma$ decay channel, to compare with the experiment carried out at ELSA. We find background from $\gamma p \to \pi^0 \pi^0 p$ followed by decay of a $\pi^0$ into two $\gamma$, recombining one $\pi^0$ and one $\gamma$, and from the $\gamma p \to \pi^0 \eta p$ reaction with subsequent decay of the $\eta$ into two photons. This background accounts for ...

The temperature and density dependence of the $\rho-\omega$ mixing amplitude has been studied from a purely hadronic model. The in-medium baryon masses and chemical potentials have been obtained at the Mean Field (MF) Level and these results have been used to calculate the mixing amplitude. It has been observed that the mixing amplitude changes substantially at high temperature and density.

An investigation of $\gamma p\to \omega p$ is presented in a constituent quark model approach. The sparse data in the large $t$ region where the resonances dominate is well described within the model, while the diffractive behavior in the small $t$ region requires an additional t-channel exchange. Taking into account the t-channel $\pi^0$ exchange, we find a good overall agreement with the available data with only 3 free parameters. Our study shows that the differential cross...

Two model-independent results on the momentum-dependence of $\rho$-$\omega$ mixing are described. First, an explicit choice of interpolating fields for the vector mesons is displayed for which both the mixing in the propagator and the isospin-breaking at the nucleon-vector meson vertices (and hence also the one-vector-meson-exchange contribution to NN charge symmetry breaking) vanish identically at $q^2=0$. Second, it is shown, using the constraints of unitarity and analytici...

We study the radiative decay $\rho^{0}\to\pi^{0}\pi^{0}\gamma$ within the framework of a phenomenological approach in which the contributions of $\sigma$-meson and $\omega$-meson intermediate states and of the pion-loops are considered. We conclude that the $\sigma$-meson amplitude provides the dominant contribution.

The study of the $\pi N\to \rho^0 N$ and $\pi N \to \omega N$ amplitudes below and close to the vector meson production threshold ($1.4<\sqrt s <1.8$ GeV)reveals a rich structure arising from the presence of baryon resonances in this energy range. These resonances are reflected in the interference pattern of the $e^+e^-$ decays of the $\rho^0$- and $\omega$-mesons produced in $\pi^- p$ and $\pi^+ n$ reactions. We discuss the shape and magnitude of the $\rho^0$-$\omega$ interf...

With the newly measurements of $X(3872) \to J/\psi\pi^+\pi^-$ from LHCb Collaboration, in addition to the dominant contribution from the $\rho^0$ meson, we perform a theoretical study on the contribution of $\omega$ meson in the $X(3872) \to J/\psi\pi^+\pi^-$ and $X(3872)\to J/\psi\pi^+\pi^-\pi^0$ processes. It is found that the recent experimental measurements on the $\pi^+ \pi^-$ invariant mass distributions can be well reproduced, and the ratio of the couplings between $X(...

We investigate the pure annihilation type radiative $B$ meson decays $B^0 \to \phi \gamma$ and $B_s \to \rho^0(\omega)\gamma$ in the soft-collinear effective theory. We consider three types of contributions to the decay amplitudes, including the direct annihilation topology, the contribution from the electro-magnetic penguin operator and the contribution of the neutral vector meson mixings. The numerical analysis shows that the decay amplitudes are dominated by the $\omega-\p...