Zurab K. Silagadze

Spherical neutral detector for VEPP-2M collider

The Spherical Neutral Detector (SND) operates at VEPP-2M collider in Novosibirsk studying e^+e^- annihilation in the energy range up to 1.4 GeV. Detector consists of a fine granulated spherical scintillation calorimeter with 1632 NaI(Tl) crystals, two cylindrical drift chambers with 10 layers of sense wires, and a muon system made of streamer tubes and plastic scintillation counters. The detector design, performance, data acquisition and processing are described.

Update of the e+e− → π+π− cross section measured by the spherical neutral detector in the energy region 400 < √s < 1000 MeV

The corrected cross section of the e^+e^-\to\pi^+\pi^- process measured in the SND experiment at the VEPP-2M e^+e^- collider is presented. The update is necessary due to a flaw in the e^+e^-\to\pi^+\pi^- and e^+e^-\to\mu^+\mu^- Monte Carlo events generators used previously in data analysis.The corrected cross section of the e^+e^-\to\pi^+\pi^- process measured in the SND experiment at the VEPP-2M e^+e^- collider is presented. The update is necessary due to a flaw in the e^+e^-\to\pi^+\pi^- and e^+e^-\to\mu^+\mu^- Monte Carlo events generators used previously in data analysis.The corrected cross section of the e+e− → π+π− process measured in the spherical neutral detector experiment at the VEPP-2M e+e− collider is presented. The update is necessary due to a flaw in the e+e− → π+π− and e+e− → μ+μ− Monte Carlo event generators used previously in data analysis.

SPECTROSCOPY AT B-FACTORIES USING HARD PHOTON EMISSION

The process of hard photon emission by initial electrons (positrons) at B-factories is discussed. It is shown that studies of the bottomonium spectroscopy will be feasible for the planned integrated luminosity of the B-factory experiments.

First observation of φ(1020)→π0π0γ decay

In the SND experiment at the VEPP-2M electron-positron collider the PHI(1020)--->PI0+PI0+GAMMA decay was studied. The branching ratio B(PHI--->PI0+PI0+GAMMA)=(1.14+-0.10+-0.12)x10^{-4} was measured. It was shown, that the F0(980)GAMMA mechanism dominates in this decay and the 4-quark model of F0(980) describes our data most consistently.Abstract In the SND experiment at VEPP-2M e + e − collider the φ (1020)→ π 0 π 0 γ decay was studied. Its branching ratio B ( φ → π 0 π 0 γ )=(1.14±0.10±0.12)·10 −4 was measured. It was shown, that f 0 (980) γ mechanism dominates in this decay. Corresponding branching ratio B ( φ → f 0 γ )=(3.42±0.30±0.36)·10 −4 was obtained.

The φ(1020) → π0π0γ decay

In the SND experiment at VEPP-2M

Study of the process e+e− → π+π− in the energy region \(400 < \sqrt s < 1000 MeV^\P \)

e^+e^-

Evidence of the φ → ηπ0γ decay

collider the

The φ→ηπ0γ decay

\phi(1020)\to\pi^0\pi^0\gamma

Study of conversion decays φ→ηe+e− and η→γe+e− in the experiment with SND detector at VEPP-2M collider

decay was studied and its branching ratio was measured:

Analysis of e+e−→π+π−π+π− and e+e−→π+π−π0π0 processes in the energy range of \(\sqrt 2 = 0.98 - 1.38 GeV\) in experiments with a spherical neutral detector

B(\phi\to\pi^0\pi^0\gamma)=(1.221\pm 0.098\pm0.061)\cdot10^{-4}