V. A. Victorov

Search for rare decays of η- and η′-mesons, and for light Higgs particles

Abstract The upper limits for the branching ratios of rare η, η′ decays have been obtained: BR( η → π 0 μ + − ) −6 , BR( η ′→ ημ + μ − ) −5 , BR( η ′→ π 0 μ + μ − ) −5 and BR( η → π 0 μ + μ − γ ) −6 (90% c.l.). These are several orders of magnitude lower than the previous limits. The analysis of the decay η ′→ ημ + μ − excludes the existence of light Higgs particles with a mass lower than 409 MeV/ c 2 .

Observation of ω → π0 μ+μ− decay

Abstract The results of studying the mass spectrum of μ + μ − γγ systems produced in π − p collisions at 25 and 33 GeV/c presented. The wide-aperture magnetic spectrometer with a hodoscope γ-detector was used to identify muon pairs and photons. There is a clear peak in the mass spectrum which corresponds to the decay ω → π 0 μ + μ − previously not observed. The branching ratio for the decay is estimated to be 9 × 10 −5 with a systematic error of 50%.

Observation of η′ → μ+μ−γ decay

Abstract The mass spectrum for μ + μ − γ systems produced in π − p interactions at 25 and 33 GeV/ c has been studied. To detect muon pairs and photons a wide-aperture magnetic spectrometer and a hodoscope γ-detector were used. In the mass spectrum a clear peak is seen corresponding to the decay η ′ → μ + μ − γ not previously observed. The branching ratio for this decay, 8 × 10 −5 , is in agreement with the η′ form-factor model, based on vector dominance.

Study of the reaction K−p → K0n at momenta of 25 and 40 GeV/c

Abstract Measurements were made of the differential cross sections for the charge exchange of K − mesons on protons at momenta of 25 and 40 GeV/ c using a high-precision spectrometer with no magnetic field. In the range 5–40 GeV/ c the reaction cross section follows a power-law dependence p K − −1.52 . In the snall momentum transfer region (− t ⪅ m π 2 ) a minimum is observed, similar to that discovered at lower energies. The differential cross sections t = 0 are considerably less than those predicted by the Regge-pole model. The parameters of the effective trajectory are determined.

Search for Θ+(1540) in exclusive proton-induced reaction \(p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N)\) at the energy of 70 GeV

AbstractA search for narrow Θ+(1540), a candidate for a pentaquark baryon with positive strangeness, has been performed in an exclusive proton-induced reaction

Study of quasiexclusive neutral meson production in pN interactions at

p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N)

=70 GeV in the deep fragmentation region

on carbon nuclei or quasifree nucleons at