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

Search for a0(980)a_0(980) and f0(980)f_0(980) mesons in ϕ→γKKˉ\phi\to\gamma K\bar K

We study the decay $\phi\to\gamma K^+K^-$ taking into account the scalar mesons production $\phi\to\gamma(f_0+a_0) \to\gamma K^+K^-$ and the final state radiation. We note that the relative sign between the final state radiation amplitude and the scalar meson production amplitude is fixed in the $K^+K^-$ loop model which describes data on the $\phi\to \gamma f_0\to\gamma\pi\pi$ and $\phi\to\gamma a_0\to\gamma\pi\eta$ decays. As consequence this model predicts the definite interference between the final state radiation and the scalar resonance production amplitudes. We calculate the mass spectra of the $\phi\to\gamma K^+K^-$ decay and the differential cross-sections for $e^+e^-\to\phi\to\gamma K^+K^-$ and for $e^+e^-\to\phi\to\gamma K^0\bar K^0$ reactions.Comment: typos remove

Analysis of the nature of the ϕ→γπη\phi\to\gamma\pi\eta and ϕ→γπ0π0\phi\to\gamma\pi^0\pi^0 decays

We study interference patterns in the $\phi\to(\gamma a_0+\pi^0\rho)\to\gamma\pi\eta$ and $\phi\to(\gamma f_0+\pi^0\rho)\to\gamma \pi^0\pi^0$ reactions. Taking into account the interference, we fit the experimental data and show that the background reaction does not distort the $\pi^0\eta$ spectrum in the decay $\phi\to\gamma\pi\eta$ everywhere over the energy region and does not distort the $\pi^0\pi^0$ spectrum in the decay $\phi\to\gamma\pi^0\pi^0$ in the wide region of the $\pi^0\pi^0$ system invariant mass, $m_{\pi\pi}>670$ MeV, or when the photon energy is less than 300 MeV. We discuss the details of the scalar meson production in the radiative decays and note that there are reasonable arguments in favor of the one-loop mechanism $\phi\to K^+K^-\to\gamma a_0$ and $\phi\to K^+K^-\to\gamma f_0$. We discuss also distinctions between the four-quark, molecular, and two-quark models and argue that the Novosibirsk data give evidence in favor of the four-quark nature of the scalar $a_0(980)$ and $f_0(980)$ mesons.Comment: 15 pages, 7 figures, title is changed, a few clarifying remarks are added, accepted for publication in Physical Review

Study of the process e+e−→π+π−π0e^+e^- \to \pi^+\pi^-\pi^0 in the energy region s\sqrt[]{s} below 0.98 GeV

The cross section of the process $e^+e^-\to \pi^+\pi^-\pi^0$ was measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2M collider in the energy region $\sqrt[]{s}$ below 980 MeV. This measurement was based on about $1.2 \times 10^6$ selected events. The obtained cross section was analyzed together with the SND and DM2 data in the energy region $\sqrt[]{s}$ up to 2 GeV. The $\omega$-meson parameters: $m_\omega=782.79\pm 0.08\pm 0.09$ MeV, $\Gamma_\omega=8.68\pm 0.04\pm 0.15$ MeV and $\sigma(\omega\to 3\pi)=1615\pm 9\pm 57$ nb were obtained. It was found that the experimental data cannot be described by a sum of only $\omega$, $\phi$, $\omega^\prime$ and $\omega^{\prime\prime}$ resonances contributions. This can be interpreted as a manifestation of $\rho\to 3\pi$ decay, suppressed by $G$-parity, with relative probability $B(\rho\to 3\pi) = (1.01\pm^{0.54}_{0.36}\pm 0.034) \times 10^{-4}$.Comment: 41 pages REVTEX and 34 figure

Electromagnetic form factors of charged and neutral kaons in an extended vector-meson-dominance model

A model is developed for electromagnetic form factors of the charged and neutral K-mesons. The formalism is based on ChPT Lagrangians with vector mesons. The form factors, calculated without fitting parameters, are in a good agreement with experiment for space-like and time-like photon momenta. Contribution of the two-kaon channels to the muon anomalous magnetic moment a_\mu is calculated.Comment: 23 pages, 11 figures, accepted for publication in Eur. Phys. J.

Energy calibration of the NaI(Tl) calorimeter of the SND detector using cosmic muons

The general purpose spherical nonmagnetic detector (SND) is now taking data at VEPP-2M $e^+e^-$ collider in BINP (Novosibirsk) in the centre of mass energy range of $0.2 \div 1.4$ GeV. The energy calibration of the NaI(Tl) calorimeter of the SND detector with cosmic muons is described. Using this method, the energy resolution of $5.5$ for 500 MeV photons was achieved.Comment: 15 pages, Latex, 11 figures (.EPS

Energy calibration of the NaI(Tl) calorimeter of the SND detector using e+e−→e+e−e^+e^- \to e^+e^- events

Calibration of the three layer NaI(Tl) spherical calorimeter of the SND detector using electron -- positron scattering events is described. Energy resolution of $5$ for 500 MeV photons was achieved.Comment: 12 pages, Latex, 8 figures (.EPS

The decays omega(782), phi(1020) to 5 pi in the hidden local symmetry approach

The decays omega -> 2pi^+ 2pi^- pi^0 and omega -> pi^+ pi^- 3pi^0 are reconsidered in the hidden local symmetry approach (HLS) added with the anomalous terms. The decay amplitudes are analyzed in detail, paying the special attention to the Adler condition of vanishing the whole amplitude at vanishing momentum of any final pion. Combining the Okubo-Zweig-Iizuka (OZI) rule applied to the five pion final state, with the Adler condition, we calculate also the phi -> 2pi^+ 2pi^-pi^0 and phi -> pi^+ pi^- 3pi^0 decay amplitudes. The partial widths of the above decays are evaluated, and the excitation curves in e^+e^- annihilation are obtained, assuming reasonable particular relations among the parameters characterizing the anomalous terms of the HLS Lagrangian. The evaluated branching ratios B(phi -> pi^+ pi^- 3pi^0)~2x10^{-7} and B(phi -> 2pi^+ 2pi^- pi^0)~7x10^{-7} are such that with the luminosity L=500 pb^{-1} attained at DAFNE phi factory, one may already possess about 1685 events of the decays phi -> 5pi.Comment: 15 pages text, 12 pages of figures. Typos corrected, clarifying remarks added. Accepted for publication in Phys.Rev.

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

Study of the process e+e−→π+π−π0e^+e^- \to \pi^+\pi^-\pi^0 in the energy region s\sqrt[]{s} from 0.98 to 1.38 GeV.}

The cross section of the process $e^+e^-\to \pi^+\pi^-\pi^0$ was measured in the Spherical Neutral Detector experiment at the VEPP-2M collider in the energy region $\sqrt[]{s} = 980 \div 1380$ MeV. The measured cross section, together with the $e^+e^-\to \pi^+\pi^-\pi^0$ and $\omega\pi^+\pi^-$ cross sections obtained in other experiments, was analyzed in the framework of the generalized vector meson dominance model. It was found that the experimental data can be described by a sum of $\omega$, $\phi$ mesons and two $\omega^\prime$ and $\omega^{\prime\prime}$ resonances contributions, with masses $m_{\omega^\prime}\sim 1490$,$m_{\omega^{\prime\prime}}\sim 1790$ MeV and widths $\Gamma_{\omega^\prime}\sim 1210$, $\Gamma_{\omega^{\prime\prime}}\sim 560$ MeV. The analysis of the $\pi^+\pi^-$ invariant mass spectra in the energy region $\sqrt[]{s}$ from 1100 to 1380 MeV has shown that for their descriptionone should take into account the $e^+e^-\to\omega\pi^0\to\pi^+\pi^-\pi^0$ mechanism also. The phase between the amplitudes corresponding to the $e^+e^-\to\omega\pi$ and $e^+e^-\to\rho\pi$ intermediate states was measured for the first time. The value of the phase is close to zero and depends on energy.Comment: 29 pages REVTEX and 17 figures, accepted for publication in Physical Review