Search

On the statistics of ~1.7 × 108 interactions of positively charged kaons on copper nuclei, coherent events of the K+π0 system production are selected. The cross sections for the Coulomb and coherent strong components and their interference in the region of the K*(892) meson are measured. The partial width for the decay K*(892) → K+γ is determined. When studying the mass spectrum of the K+π0 system, an effect which can be interpreted as the interference of the chiral anomaly and the K*(892) s-channel amplitudes is found. This gives an estimate for the ratio of the observed amplitude of the chiral anomaly to the theoretical one: Aexp/Ath = 0.9 ± 0.24(stat.) ± 0.3(syst.).

Recent results from OKA setup concerning form factor studies in Ke3 decay are presented. About 5.25 M events obtained for decays of 17.7 GeV/cK+ are selected for the analysis. The linear and quadratic slopes for the decay form factor f+(t) are measured: λ'+ = 2.95 ± 0.022 ± 0.018 × 10 -2 for the linear slope fit and λ+ = 2.611 ± 0.035 ± 0.028 × 10 -2, λ"+ = 1.91 ± 0.19 ± 0.14 × 10 -3 for the quadratic one. The scalar and tensor contributions are compatible with zero. Several alternative parametrizations are tried: the Pole fit parameter is found to be M V = 891 ± 3 MeV; the parameter of the dispersive parametrization is measured to be Λ+ = 2.458 ± 0.018 × 10-2.

The parameters of the Dalitz diagram for the decay η′ → ηπ0π0 in a generalized and a linear representation were determined by using a statistical sample of 15 × 103 events. A charge-exchange reaction at a momentum of 32 GeV/c was a source of monoenergetic η′ mesons. The experiment was performed with the aid of the GAMS-4π spectrometer.

An experiment performed with the GAMS-4π spectrometer resulted in observing 235 ± 45 events of the decay η′ → 3π 0. The respective charge-exchange reaction at a momentum of 32.5 GeV/c was used as a source of η′ mesons. The decay branching ratio was found to be Br(η′ → 3π 0) = (1.8 ± 0.4) × 10−3. The slope parameter of the square of the respective matrix element in the linear approximation proved to be β = −0.59 ± 0.18.

Searches for rare and forbidden neutral decays of η mesons are performed at the GAMS-4π facility. A charge-exchange reaction at an initial momentum of 32.5 GeV/c was used as a source of 3.7 × 106 η mesons. The following upper limits are established at a 90% confidence level: Br(η → 3γ) < 1.6 × 10−4, Br(η → 4γ) < 2.8 × 10−4, Br(η → π0π0) < 3.5 × 10−4, Br(η → π0π0γ) < 1.7 × 10−3, Br(η → π0π0γγ) < 4.0 × 10−3, Br(η → 3π0γ) < 2.4 × 10−4, and Br(η → 4π0) < 2.0 × 10−5.

The ηη system produced in charge-exchange π−p interaction at a momentum of 32.5 GeV/c is studied in an experiment performed with the GAMS-4π spectrometer at the 70-GeV accelerator of the Institute for High-Energy Physics (IHEP, Protvino). A partial-wave analysis is performed in the mass range between 1.1 and 3.9 GeV for −t

We consider potential experiments at the U-70 accelerator (Institute for High Energy Physics, Protvino) on the search and study of rare neutral η-, ω-, and η"-meson decays that are critical for the modern theory, at a qualitatively new level of statistical accuracy. A special setup with the use of meson tagging and electromagnetic calorimetry on PbWO4crystals is offered for this experiment. The neural net approach was invoked at the stage of data processing. The Monte Carlo simulation of the experiment demonstrated its high sensitivity to rare-decay detection, which far exceeds the existing world results.

A monitoring system for the prototype of a Photon Spectrometer based on the lead-tungstate crystals of the ALICE experiment at the LHC collider. Light-emitting diodes are used as a source of light test signals simulating scintillations in crystals. The system provides individual control of the spectrometer's 64 channels. A relative channel monitoring stability of 1.2 × 10–3 was achieved upon exposing the spectrometer to a beam for a period of 100h.