Yu. A. Tikhonov

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.

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

AbstractThe cross section of the process e+e− → π+π− was measured in the spherical neutral detector experiment at the VEPP-2M collider in the energy region

The KEDR detector

400 < \sqrt s < 1000 MeV

Measurement of the τ lepton mass at the KEDR detector

. This measurement was based on about 12.4 × 106 selected collinear events, which include 7.4 × 106e+e− → e+e−, 4.5 × 106e+e− → π+π−, and 0.5 × 106e+e− → μ+μ− selected events. The systematic uncertainty of cross section determination is 1.3%. The ρ-meson parameters were determined as mρ = 774.9±0.4±0.5 MeV, Γρ = 146.5±0.8±1.5 MeV, and σ(ρ → π+π−) = 1220 ± 7 ± 16 nb and the parameters of the G-parity suppressed decay ω → π+π− as σ(ω → π+π−) = 29.9 ± 1.4 ± 1.0 nb and φρω = 113.5±1.3±1.7°.

The results of vacuum phototriodes tests

Abstract KEDR is a general-purpose detector for experiments at the VEPP-4M e + e − -collider in the energy range 2 E =2.0– 12 GeV . All detector subsystems (except the aerogel Cherenkov counters) have been installed into the detector at VEPP-4M. Some preliminary data have been taken in the energy region of the J/Ψ meson. The tuning of the detector and the VEPP-4M collider is in progress. Preliminary results on the detector performance are presented. The future experimental program for the KEDR detector is discussed.

Luminosity measurement with the MD-1 detector at VEPP-4

The KEDR detector is a universal magnetic detector designed for studying the c- and b-quarks and two-photon physics, and is employed at the VEPP-4M e + e − collider. A specific feature of the experiment is the measurement of absolute beam energy using two methods: the resonant depolarization and the faster but less precise Compton backscattering of laser photons. This allowed a large series of measurements to be performed, in which the accuracy of determination of such fundamental parameters of particles as mass and total and leptonic widths was improved.

Investigation of an electromagnetic calorimeter based on liquid krypton

Data analysis of an experiment in which photon splitting in atomic fields was observed is presented. The experiment was performed at the tagged photon beam of the ROKK-1M facility at the VEPP-4M collider. In the energy region of 120-450 MeV, statistics of 1.6x10(9) photons incident on the BGO target was collected. About 400 candidate photon-splitting events were reconstructed. Within the attained experimental accuracy, the experimental results are consistent with the calculated exact atomic-field cross section. The predictions obtained in the Born approximation differ significantly from the experimental results.

A high precision measurement of the ϒ, ϒ′ and ϒ″-meson masses

A precise τ lepton mass measurement performed at the VEPP-4M collider with the KEDR detector is reported. The mass value is evaluated from the τ+τ− cross section behavior around the production threshold. The result based on 6.7 pb−1 of data is mτ = 1776.81−0.23+0.25 ± 0.15 MeV. Using 0.8 pb−1 of data collected at the ψ′ peak, we have also determined that ΓeeBττ(ψ′) = 9.0 ± 2.6 eV.