The new analysis of the KLOE data on the phi->eta pi0 gamma decay

In this paper we present the fit to the recent high-statistical KLOE data on the phi -> eta pi^0 gamma decay. This decay mainly goes through the a_0 gamma intermediate state. The obtained results differ from those of the previous fits: data prefer a high a_0 mass and a considerably large a_0 coupling to the K\bar K}.Comment: 11 pages, 2 figure

Proposed Search for a00(980)−f0(980)a^0_0(980)-f_0(980) Mixing in Polarization Phenomena

The $K^+$ and $K^0$ meson mass difference induces the mixing of the $a^0_0(980)$ and $f_0(980)$ resonances, the amplitude of which, between the $K^+K^-$ and $K^0\bar K^0$ thresholds, is large in magnitude, of the order of $m_{K}\sqrt{m^2_{K^0}-m^2_{K^+}}\approx\sqrt\alpha m^2_K$, and possesses the phase sharply varying by about 90$^\circ$. We suggest performing the polarized target experiments on the reaction $\pi^-p\to\eta\pi^0n$ at high energy in which the fact of the existence of $a^0_0(980)-f_0(980)$ mixing can be unambiguously and very easily established through the presence of a strong jump in the azimuthal asymmetry of the $\eta\pi^0$ $S$ wave production cross section near the $K\bar K$ thresholds. The presented estimates of the polarization effect to be expected in experiment are to a great extent model independent.Comment: RevTeX, 9 pages, 1 figure. A number of typographical and grammatical errors correcte

New Data from SND Detector in Novosibirsk

The current status of experiments with SND detector at VEPP-2M e^+e^- collider in the energy range 2E_0=400-1400 MeV and recent results of data analysis for $\phi$, $\omega$ and $\rho$ decays and e^+e^- annihilation into hadrons are presented.Comment: 7 pages, 8 figures, Latex2e, uses espcrc1.sty. Talk given at 8th International Conference on Hadron Spectroscopy (HADRON 99), Beijing, China, 24-28 Aug 199

Nature of the a_0(980) Meson in the Light of Photon-Photon Collisions

New high-statistics Belle data on the reaction \gamma\gamma\to\pi^0\eta are analyzed to clarify the two-photon production mechanisms and the nature of the a_0(980) meson. The obtained solution for the amplitude \gamma\gamma\to\pi^0\eta is consistent with the chiral theory expectation for the \pi\eta scattering length, with the strong coupling of the a_0(980) to the \pi\eta, K\bar K, and \pi\eta' channels, and with a key role of the rescattering mechanisms a_0(980)\to(K\bar K+ \pi^0\eta+\pi^0\eta')\to\gamma\gamma in the a_0(980)\to\gamma\gamma decay. Such a picture argues in favor of the q^2\bar q^2 nature of the a_0(980) meson and is in agreement with the properties of its partners, the \sigma_0(600) and f_0(980) mesons, in particular, with those that manifest themselves in \gamma\gamma\to\pi\pi. An important role of the vector meson exchanges in the formation of the nonresonant background in \gamma\gamma\to\pi^0\eta is also revealed. The preliminary information on the reaction \pi^0\eta\to\pi^0\eta is obtained.Comment: 7 pages, 5 figures, minor corrections and some comments adde

The ρ±−ρ0\rho^{\pm}-\rho^0 Mass Splitting Problem

It is discussed the problem of the $\rho^\pm-\rho^0$ mass splitting. It is suggested to use the $\phi\to\rho\pi\to 3\pi$ decay to measure the $\rho^{\pm}-\rho^0$ mass splitting.Comment: 7 pages, revtex, a few typos fixed, to be published in Pis'ma v ZHETF, V. 69, No 1, pp. 8-11, 10 January 199