The pion radiative scattering (π-p → π-pγ) has been studied at 43 GeV in the interval 0.2 < |tp| < 0.4 (GeV/c)2 of the momentum transfer squared to the proton and in the range of photon energy 2 < ω < 40 GeV. Calculations based on Low theorem agree well with measured ω, tp and mπγ (final πγ-invariant mass) differential cross-sections. The results obtained extend the validity of Low approach to the radiative scattering at high energies.

In the diffraction dissociation of π− into μ+μ−π− on a Cu nucleus at 50 GeV/c, the cross section\(\sigma _{\mu ^ + \mu ^ - \pi ^ - } \) for the 1+S(ρ0π) wave was measured. The branching ratio of ρ0→μ+μ− could be calculated from the ratio of this and the corresponding cross sections in the diffraction dissociation of π− into π+π−π−. The obtained value\(BR_{\rho ^0 \to \mu ^ + \mu ^ - } = (4.6 \pm 0.2_{stat^ \pm } \pm 0.2_{syst} )10^{ - 5} \) is in good agreement with the branching ratio\(BR_{\rho ^0 \to e^ + e^ - } \), as expected ifeμ universality holds.

In the reaction of π- dissociation into a μ+μ-π- system on a Cu nucleus, a clear enhancement in the ρ0π- effective-mass distribution has been observed in the π2(1680) region. Partial-wave analysis shows that this enhancement is due to the P-wave and has a resonant nature. Coherent and incoherent cross-sections for this enhancement have been measured.

The vertex \ensuremath{\gamma}\ensuremath{\rightarrow}3\ensuremath{\pi} has been investigated in the reaction of pion pair production by pions in the nuclear Coulomb field, ${\ensuremath{\pi}}^{\ensuremath{-}}$+(Z,A)\ensuremath{\rightarrow}${\ensuremath{\pi}}^{\ensuremath{-}}$+${\ensuremath{\pi}}^{0}$+(Z,A), in the region of low-invariant-mass ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\pi}}^{0}$ pairs. The experiment has been carried out in the 40-GeV pion beam of the IHEP accelerator (Serpukhov) with the SIGMA spectrometer. We have measured for the first time the cross section of the reaction in the region of momentum transfer squared ${q}^{2}$2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$ (GeV/c${)}^{2}$, \ensuremath{\sigma}/${Z}^{2}$=1.63\ifmmode\pm\else\textpm\fi{}0.23\ifmmode\pm\else\textpm\fi{}0.13 nb, and the \ensuremath{\gamma}\ensuremath{\rightarrow}3\ensuremath{\pi} coupling constant ${F}^{3\ensuremath{\pi}}$=12.9\ifmmode\pm\else\textpm\fi{}0.9\ifmmode\pm\else\textpm\fi{}0.5 ${\mathrm{GeV}}^{\mathrm{\ensuremath{-}}3}$, where the first (second) error is statistical (systematic). The obtained result agrees with the calculations based on the Wess-Zumino-Witten effective Lagrangian. The hypothesis of chiral anomalies and the color-SU(3) quark symmetry are confirmed.

In the reaction of π- dissociation into a μ+μ-π- system on a Cu nucleus, a clear enhancement in the ρ0π- effective-mass distribution has been observed in the π2(1680) region. Partial-wave analysis shows that this enhancement is due to the P-wave and has a resonant nature. Coherent and incoherent cross-sections for this enhancement have been measured.

The pion radiative scattering πZ→πZγ at 40 GeV was investigated. Coulomb scattering-i.e. pion Compton-effect-dominates for small fourmomentum transfers in this reaction. In our previous paper we found the pion polarizability to beβ π =(−6.8±1.4)·10−43, cm3, where we assume following the theory that the sum of electrical and magnetic polarizabilities (α π +β π )≃0. More complete analysis of our data is done in order to test this assumption. The result for (α π +β π ) is in agreement with theoretical predictions.

The reaction π−A→Aπ− γ at 40 GeV/c was studied on “Sigma” spectrometer on six different nuclear targets in the region of four-momentum transfer |t|<0.05 (GeV/c)2. A phenomenon of elastic scattering of pions on the nuclear Coulomb field photons was observed, its total and differential cross sections were measured. The cross section of Compton effect on π−-meson was measured.

About 7 × 103 events of Compton effect on pion in the reaction π−A → Aπ−γ st 40 GeV/c were detected and for the first time the charged pion polarizability was obtained απ = (6.8 ± 1.4) × 10−43 cm3.

Results of the experimental study of inclusive φ meson production off berillium nuclei by 70 GeV/c protons in the beam fragmentation region x > 0.41 are presented. Fitting of the measured differential cross sections to the forms dσdx ∼ (1 − x)nx and dσdp2t ∼ exp(−bp2t) gives the parameters n = 6.0 ± 1.7 and b = (2.4 ± 0.7) (GeV/c)−2. In the framework of a quark-parton model the measured φ meson x-distribution suggests that in the region of x > 0.41 nearly 90% of the φ mesons are produced via a strange sea quark fusion. The ratio of the OZI-forbidden and OZI-allowed transition coupling constants has been found to be ten times smaller than the same ratio calculated from the partial decay widths. The total inclusive cross section is estimated to be σ(pN → φX) = (0.7 ± 0.2) × 10−27 cm2.

The A-dependence of J/ψ inclusive production by 43 GeV/c π−-mesons was measured to be σ = (18 ± 6)A(0.92±0.06) nb/nucleus for x > 0.

Invariant mass spectrum of μ+μ− pairs produced by 70 GeV/c protons in Be target are presented. Distinct enhancements in the mass regions of ϱ, ω mesons, φ meson and J/ψ particle are observed. For J/ψ production x and p⊥2 distributions are given. The total cross section for the reaction p + Be → (Jψ → μ+μ−) + … is equal to 9.5 ± 2.5 nb/nucleus.

The paper presents the results on differential cross sections for elastic scattering of 7+-, K+-mesons and protons on protons in the 4-momentum transfer squared range 0·08 ≦¦t¦≦ ≦1·0 (GeV/c)2 and incident particle momentum of 29 and 43 GeV/c for pions and kaons and 29, 43, 50 and 65 GeV/c for protons. The measurements were taken with the spectrometer Sigma, installed in the positive beam of the IHEP accelerator.