The charge-exchange reaction π ^- Be→A ω (782)ϕ (1020) with ω→π ^+π ^-π ^0 and ϕ→ K^+K^- is studied with the upgraded VES facility (U-70, Protvino) using a 29 GeV pion beam. The distribution of the ωϕ invariant mass shows a near-threshold enhancement. Partial-wave analysis reveals that an isoscalar scalar state with J^PC=0^++ dominates in this mass region. Considering the observed signal as an f_0 resonance, and using the one-pion-exchange model, the product of the branching fractions into two channels Br(f_0→ππ ) Br(f_0→ωϕ ) is measured. Based on this value, a large partial width is found for the radiative decay of J/ψ into this state, which suggests a significant glueball component. The result is discussed under alternative assumptions concerning an identification of the observed signal as f_0(1710) or f_0(1770) .

The charge-exchange reaction π^-p → n ω(783)ϕ(1020), ω→π^+π^-π^0, ϕ→ K^+K^- is studied with the upgraded VES facility (U-70, Protvino) in the interaction of a 29 GeV pion beam with a beryllium target. The distribution over the invariant mass of the system M_ωϕ shows a near-threshold signal. A partial wave analysis reveals that the scalar state (J^PC=0^++) dominates in this mass region. The observed signal can be described with a contribution of the known resonance f_0(1710). Using OPE approximation for the reaction π^-p → n f_0(1710) the product of branching fractions is found to be: Br(f_0(1710)→ππ)· Br(f_0(1710)→ωϕ) = (4.8 ± 1.2) · 10^-3.

A 32-channel 12-bit ADC-32ATC analog-to-digital conversion module with signal shape digitization at 40 MHz, which was been developed for the VES experiment at the U-70 accelerator, is presented. The analog shapers for this module, the measurement methods, the data-processing techniques, and the experience gained in using this module in the VES experiment are described. The module is intended to register single pulses with a stable shape or a linear combination of a few such pulses with positive coefficients. It can be used for calorimeters, as well as for Cherenkov and scintillation counters, in fixed-target experiments in high-energy physics.

A data acquisition system of the OKA experiment on studying rare kaon decays on the U-70 accelerator is described. The basis of the blocked data acquisition system was the high-speed multichannel information system MISS with autonomous controllers that read out the front-end electronics in the sequential data reading mode and buffering data during the accelerator burst. Data stored in the buffer memory are read out and processed at the end of the accelerator burst. The DATE package builds subevents from event fragments and events from subevents via the event building network. The event building network with the star topology is made with 1GbE-interfaces and 24 × 1 Gb E-switch. The GlusterFS cluster file system underlies the distributed storage system.

A complex of the new electromagnetic calorimeter (ECAL-2) for the VES setup is described. It is composed of 1592 “shashlik” type counters consisting of a set of lead−scintillator plates, high-voltage supplies based on cascade voltage multipliers for FEU-84 photomultiplier tubes, an LED-based monitoring system, a slow control system, and a pulse-height analysis system. The procedures of ECAL-2 calibration and online monitoring are described.

Preliminary results obtained by studying K − π −, K − π − π 0, and K − π − η systems in the VES experiment are presented. No statistically significant signals from possible resonances were observed in two- and three-particle mass spectra of doubly charged (sub)systems.

Experimental investigations of candidates for hybrid mesons in the VES experiment at the Institute for High Energy Physics (Protvino) are surveyed. The data in question concern π1 (1400) characterized by the exotic quantum numbers of J PC = 1−+ and observed in the ηπ− final state; JPC = 1−+π1 (1600) in the ηπ−, b1 (1235)π, and f1(1285)π− final states; and J PC = 0−+π(1800) in the f0(980)π−, f0(1300)π−, f0(1500)π−, and a 0 − (980)η final states. New results are given along with data published previously.

Form factors measured for the decay η ′ å ηπ − π + in π − A å η′π − A * reactions at a beam momentum of p π = 28 GeV are presented. The distribution in Dalitz variables for 7000 decay events is described well within a linear and a nonlinear parametrization of the relavant matrix element. The slope parameter in the variable y differs from zero significantly. It is Re α = −0.072±0.012 (stat.)±0.006 (syst.) in the linear and a = −0.120±0.027 (stat.)±0.015 (syst.) in the nonlinear parametrization. In this decay, the C -violation parameter is compatible with zero, c = 0.021±0.024.

Results obtained by investigating the reaction π − p → η ′ π 0 n at the VES spectrometer (Institute for High Energy Physics, Protvino) are presented. The effective-mass spectrum and angular distributions of η ′ π 0 events are compared with their counterparts for ηπ 0 and η ′ π − events selected from the same data sample. The ratio R of the branching fractions for the decays of a 2 0 (1320) mesons into η ′ π and ηπ is measured. The result is R =0.047±0.018, which agrees with the value measured previously for a 2 − . An investigation of P -wave production in the η ′ π 0 and ηπ 0 systems over the effective-mass interval 1.45–1.9 GeV/ c 2 leads to the conclusion that the coupling of the exotic object π 1 (1600) to the ρπ channel is suppressed in relation to its coupling to the η ′ π or the b 1 (1235) π channel.

Results obtained by investigating the reaction pi(-)p --> eta'pi(0)n at the VES spectrometer (institute for High Energy Physics, Protvino) are presented. The effective-mass spectrum and angular distributions of eta'pi(0) events are compared with their counterparts for etapi' and eta'pi(-) events selected from the same data sample. The ratio R of the branching fractions for the decays of a(2)(0)( 1320) mesons into eta'pi and etapi is measured. The result is R = 0.047 +/- 0.018, which agrees with the value measured previously, for a(2)(-). An investigation of P-wave production in the eta'pi(0) and etapi(0) systems over the effective-mass interval 1.45-1.9 GeV/c(2) leads to the conclusion that the coupling of the exotic object pi(1)(1600) to the ppi channel is suppressed in relation to its coupling to the eta'pi or the b(1)(1235)pi channel. (C) 2004 MAIK "Nauka/Interperiodica".

The pion-induced formation of the low-mass system eta pi(-) in the Coulomb field of a beryllium nucleus has been investigated. The measured cross section for the reaction pi(-)Be --> eta pi(-)Be is compared with a theoretical prediction:based on the observed width of the decay eta --> pi(+)pi(-)gamma.

A partial-wave analysis of the system omega pi(-)pi(0) has been performed for the reaction pi(-) + A --> pi(+)2 pi(-)2 pi(0) + A* induced by 37-GeV negative pions. A resonance structure with a mass of M approximate to 1.74 GeV and quantum-number values of J(P)M(eta) = 0(-)0(+) has been observed in the invariant-mass distribution for this system. The branching fraction for a(2)(1320) decay into omega pi(-)pi(0) has been determined. A broad structure at M approximate to 1.7 GeV has been revealed in the J(P)M(eta) = 2(+)1(+) partial wave, First observations of the decays pi(2)(1670) --> omega rho(-) and a(4)(2040) --> omega rho(-) are reported.

The diffractive production of the eta eta pi(-) system by pi(-) mesons on beryllium nuclei is investigated with a VES detector. The mass spectrum in the range M(eta eta pi)(-)=1.5-2.0 GeV is found to be dominated by the J(PC)=0(+) wave in the a(0)(-)(980)eta channel. This wave has a resonant behavior with parameters M=1840+/-10(stat)+/-10(syst.)MeV and gamma=210+/-30(stat.)+/-30(syst.)MeV. A structure observed in the eta eta mass spectrum may be described in terms of an isobar state with quantum numbers J(P)=0(+) and parameters M approximate to 1460 MeV and (G)amma approximate to 100 MeV.