[en] On the basis of experimental data from the 6-m spectrometer of the Institute of Theoretical and Experimental Physics (ITEP, Moscow), an amplitude analysis of 40 553 events of the reaction π^-p ^→ K_SK_Sn induced by a negatively charged pion of energy 40 GeV is performed over a broad momentum transfer range by using a new procedure. The results for vertical bar t vertical bar > 0.1 GeV² are obtained for the first time. In particular, resonances of mass 1700 and 1900 MeV and width 120 MeV are discovered in the D₊ wave (there were no such resonances for vertical bar t vertical bar < 0.1 GeV²). In the region of low momentum transfers, the S wave exhibits a structure that lies in the mass region around 1370 MeV and which requires three resonances for its explanation. Two of these (that of mass 1234 ± 6 MeV and width 47 ± 33 MeV and that of mass 1478 ± 6 MeV and width 119 ± 10 MeV) were found in the studies of A. Etkin et al. [Phys. Rev. D 25, 2446 (1982)] and O.N. Baloshin et al. {Yad. Fiz. 43, 1487 (1986) [Phys. At. Nucl. 43, 959 (1986)]}. The third has a mass of 1389 ± 9 MeV and a width of 30 ± 24 MeV. At high momentum transfers, the S wave is found to feature resonances that have the following parameters: M = 1328 ± 8 MeV and Γ = 237 ± 20 MeV, M = 1440 ± 6 MeV and Γ = 121 ± 15 MeV, and M = 1776 ± 15 MeV and Γ 250 ± 30 MeV. For the D₀ wave, it is found that, in addition to the well-known resonances f₂, a₂, and f'₂, there appear the following resonances in this wave: a resonance of mass 2005 ± 12 MeV and width 209 ± 32 MeV and a resonance of mass 2270 ± 12 MeV and width 90 ± 29 MeV at low vertical bar t vertical bar and a resonance of mass 1659 ± 6 and width 152 ± 18 and a resonance of mass 2200 ± 13 MeV and width 91 ± 62 MeV at high vertical bar t vertical bar

[en] Results are presented that were obtained by studying the narrow resonance of mass about 1450 MeV. This state was discovered in the system of two K_s-mesons. The experimental data subjected to the analysis here come from the 6-m spectrometer (MIS ITEP) created at the Institute of Experimental and Theoretical Physics (ITEP, Moscow) and irradiated with a 40-GeV beam of negatively charged pions from the U-70 accelerator at the Institute for High Energy Physics (IHEP, Serpukhov) with the aim of studying π^-p and π^-C interactions. The statistical significance is better than six standard deviations. The mass and width of the observed meson are M = 1449.5 ± 2.0 ± 3.0 MeV and s = 7.5 ± 1.5 MeV, respectively, the product of the cross section for its formation and the relevant branching ratio 25_-5⁺²⁵ (stat.) ± 4(syst.) nb. The spin-parity J^pc is 0⁺⁺ or 2⁺⁺. Seeing its very narrow width this resonance is likely to be cryptoexotics (see [1], [2] for details)

[en] Results obtained by studying a previously unknown narrow meson of mass about 1731 MeV are presented. This state was found in a system of two K_S mesons. The experimental-data set subjected to the present analysis was obtained with a 6-m spectrometer of the Institute of Theoretical and Experimental Physics (ITEP, Moscow). The statistical sample of event of double K_S-meson production was accumulated in π^-p interactions by using a beam of 40-GeV pions from the U-70 accelerator of the Institute of High Energy Physics (IHEP, Protvino). There are 58 events at the respective maximum, its statistical significance being close to six standard deviations. The parameters of the observed meson are the following; the mass is M = 1731 ± 2.5 MeV, the width is σ = 3.2 ± 2 MeV, and the product of the production cross section and the respective branching ratio is not less than 20 nb. The fact that the observed meson is extremely narrow does not have a satisfactory theoretical explanation

[en] Analysis of the 1700-1800 MeV/c² mass region of the K_SK_S-meson system was carried out on 30000 events obtained with the neutral trigger. A resonance state with mass 1775 MeV/c² and width about 12 MeV/c² is clearly observed at selection of the transverse momentum t>0.25(GeV/c)². Another sample of events with additional π⁰ shows peak near threshold due to a⁰(f⁰) in the same K_SK_S system in contrast to elastic reaction π^-p→K_SK_Sn

[en] Several narrow resonance features in the system of two K_S mesons were found on the basis of experimental data obtained by using the 6-m spectrometer of the Institute of Theoretical and Experimental Physics (ITEP, Moscow). Three resonances, X(1070), X(1545), and f_J(2220), are considered in the present study. An interference with the background is observed for the X(1545) resonance. It is shown that X(1070) and f_J(2220) resonances are produced under nearly identical kinematical conditions characterized by high transverse momenta and the production of accompanying extra pions.

[en] The history of the development and construction of the ITEP-MIS 6-m magnetic spectrometer is reported. Research studies performed by the ITEP-MIS group over a period of more than 30 years of spectrometer existence is surveyed. The results obtained by studying the narrow resonances f_j(2220) and X(1070) are presented