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The article notes the public danger of the facts of public terrorism justification, as well as its propaganda, since recently the development of information technologies has also promoted this phenomenon. It is also indicated that among the measures to prevent the ideology of terrorism, the main importance belongs to the criminal-legal regulation on committing a crime in this area. The article defines measures to prevent the ideology of terrorism at the general social, special criminological and individual levels. The main focus is put on the methods of special criminological prevention of the ideology of terrorism. At this, the role of pedagogical collectives of secondary schools, colleges and higher educational institutions in the system of terrorism ideology prevention is analyzed. Possible practical forms of extracurricular work with students, teachers and parents of students, aimed at preventing the expansion of terrorism ideology in the field of education are indicated. At this, the article gives examples of preventive activities carried out in the form of: lectures by police officers, prosecutors and law school teachers in educational institutions; professional development of teachers of educational institutions, as well as state and municipal employees on implementing the tasks in the field of terrorism ideology preventing among young people; conducting scientific seminars on the problems of terrorism and extremism; developing and teaching a special course "Legal Foundations for Countering Extremism and Terrorism" not only for lawyers, but for students of other specialties as well.

$\gamma p \rightarrow K^+ \Lambda$ differential cross sections and recoil polarisation data from threshold for extremely forward angles are presented. The measurements were performed at the BGOOD experiment at ELSA, utilising the high angular and momentum resolution forward spectrometer for charged particle identification. The data discriminates between conflicting results in the world data set and enable extraction of the cross section as the minimum momentum transfer to the recoiling hyperon is approached., Comment: 12 pages (including a 2 page appendix), 14 figures

The BGO-OD experiment at the ELSA accelerator facility uses an energy tagged bremsstrahlung photon beam to investigate the excitation structure of the nucleon via meson photoproduction. The setup with a BGO calorimeter surrounding the target and an open dipole spectrometer covering the for ward region is ideally suited for investigating low momentum transfer processes, in particular in strangeness photoproduction. The associated photoproduction of K0S and hyperons is essential to understand the role of K* exchange mech anisms. A cusp-like structure observed in the yp → K0SΣ+ reaction at the K* threshold is described by models including dynamically generated resonances from vector meson-baryon interactions. Such interactions are pre dicted to give a peak like structure in K0SΣ0 photoproduction off the neutron. A very preliminary cross section is determined and compared to the prediction, the results appear to support the model

The BGO-OD experiment at the ELSA accelerator facility uses an energy tagged bremsstrahlung photon beam to investigate the excitation structure of the nucleon. The setup consists of a highly segmented BGO calorimeter surrounding the target, with a particle tracking magnetic spectrometer at forward angles. BGO-OD is ideal for investigating low momentum transfer processes due to the acceptance and high momentum resolution at forward angles. In particular, this enables the investigation of strangeness photoproduction where t-channel exchange mechanisms play an important role. This also allows access to low momentum exchange kinematics where extended, molecular structure may manifest in reaction mechanisms. First key results at low $t$ indicate a cusp-like structure in $K^+\Sigma^0$ photoproduction at $W = 1900$\,MeV, line shapes and differential cross sections for $K^+\Lambda$(1405)$\rightarrow K^+\Sigma^0\pi^0$, and a peak structure in $K^0_S\Sigma^0$ photoproduction. The peak in the $K^0_S\Sigma^0$ channel appears consistent with meson-baryon generated states, where equivalent models have been used to describe the $P_C$ pentaquark candidates in the heavy charmed quark sector., Comment: Proceedings of The 12th International Workshop on the Physics of Excited Nucleons (NSTAR 2019)

The unexpected nodal structure of the beam asymmetry recently reported by the GRAAL collaboration in η′ photoproduction very close to threshold could be explained by a previously unobserved narrow resonance. The BGO-OD experiment is ideally suited to verify this measurement via the detection of forward going charged particles which in the threshold region of interest allows the identification of the reaction γp → η′ p solely based on the proton going in the forward direction. This yields unprecedented statistics if, in the missing mass analysis of the η′ meson, the background can be sufficiently well controlled. Preliminary results using a linearly polarised photon beam are shown. The reaction γp → η′ p was identified in the BGO forward spectrometer, with simulated data used to seperate signal and background.

The article describes the formation and development of the institution of criminal liability for crimes related to drug trafficking in the domestic criminal legislation. Based on the analysis of changes in the criminal law in the regulation of social relations in the field of drug trafficking, an attempt is made to trace the process of formation of a modern criminal law concept of combating their illegal trafficking

The γ p → K + Σ 0 differential cross section at extremely forward angles was measured at the BGOOD experiment. A three-quarter drop in strength over a narrow range in energy and a strong dependence on the polar angle of the K + in the centre-of-mass of the reaction is observed at a centre-of-mass energy of 1900 MeV. Residing close to multiple open and hidden strangeness thresholds, the structure appears consistent with meson-baryon threshold effects which may contribute to the reaction mechanism.

Observation of a narrow structure at W ∼ 1.68 GeV in the excitation functions of some photon- and pion-induced reactions may signal a new narrow isospin-1/2 N(1685) resonance. New data on the γN → πηN reactions from GRAAL seems to reveal the signals of both N+(1685) and N0(1685) resonances.

Different interpretations of narrow structures at $W\sim 1.68$ and $W\sim 1.72$ GeV observed in several reactions are discussed. It is questionable whether interference phenomena could explain the whole complex of experimental findings. More probable hypotheses would be the existence of one or two narrow resonances $N(1685)$ and $N(1726)$ and/or the sub-threshold virtual $K\Sigma$ and $\omega p$ production (cusps)., Comment: Published version

The BGO-OD experiment at the ELSA accelerator facility uses an energy tagged bremstrahlung photon beam to investigate the excitation structure of the nucleon. The setup consists of a highly segmented BGO calorimeter surrounding the target, with a particle tracking magnetic spectrometer at forward angles. BGO-OD is ideal for investigating low momentum transfer processes due to the acceptance and high momentum resolution at forward angles. In particular, this enables the investigation of strangeness photoproduction where t-channel exchange mechanisms play an important role. This also allows access to a kinematic region where extended, molecular structure may manifest in reaction mechanisms. The extensive strangeness photoproduction programme includes the photoproduction of neutral and charged kaons using both hydrogen and deuterium targets.

Since the discovery of the Λ(1405), it remains poorly described by conventional constituent quark models, and it is a candidate for having an “exotic” meson-baryon or “penta-quark” structure, similar to states recently reported in the hidden charm sector.The Λ(1405) can be produced in the reactionγpK+Λ(1405). The pure I=0 decay mode into Σ0π0is prohibited for the mass-overlapping Σ(1385). Combining a large aperture forward magnetic spectrometer and a central BGO crystal calorimeter, the BGO-OD experiment is ideally suited to measure this decay with theK+in the forward direction. Preliminary results are presented.*Supported by DFG (PN 388979758, 405882627)

Quasi-free photoproduction of $ \eta{^\prime}$ -mesons off nucleons bound in the deuteron has been measured with the combined Crystal Barrel - TAPS detector. The experiment was done at a tagged photon beam of the ELSA electron accelerator in Bonn for incident photon energies from the production threshold up to 2.5GeV. The $ \eta{^\prime}$ -mesons have been detected in coincidence with recoil protons and recoil neutrons. The quasi-free proton data are in good agreement with the results for free protons, indicating that nuclear effects have no significant impact. The coincidence with recoil neutrons provides the first data for the $ \gamma$ n $ \rightarrow$ n $ \eta{^\prime}$ reaction. In addition, also first estimates for coherent $ \eta{^\prime}$ -production off the deuteron have been obtained. In agreement with model predictions, the total cross-section for this channel is found to be very small, at most at the level of a few nb. The data are compared to model calculations taking into account contributions from nucleon resonances and t -channel exchanges

Photoproduction of $\eta$ mesons off $^{12}$C, $^{40}$Ca, $^{93}$Nb, and $^{nat}$Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2 GeV. The experiment was performed at the Bonn ELSA accelerator with the combined setup of the Crystal Barrel and TAPS calorimeters. It aimed at the in-medium properties of the S$_{11}$(1535) nucleon resonance and the study of the absorption properties of nuclear matter for $\eta$ mesons. Careful consideration was given to contributions from $\eta\pi$ final states and secondary production mechanisms of $\eta$-mesons e.g. from inelastic $\pi N$ reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross section $\sigma_{N\eta}$ for $\eta$ mesons is constant over a wide range of the $\eta$ momentum. The comparison of the excitation functions to data off the deuteron and to calculations in the framework of a BUU-model show no unexplained in-medium modifications of the S$_{11}$(1535)., Comment: Accepted for publication in Eur. Phys. J. A

The BGO-OD experiment at the ELSA accelerator facility uses an energy tagged bremstrahlung photon beam to investigate the excitation spectrum of the nucleon. The setup consists of a highly segmented BGO calorimeter surrounding the target, with a particle tracking magnetic spectrometer at forward angles. BGO-OD is ideal for investigating the photoproduction of hadrons of non-zero strangeness. The high momentum resolution at forward angles covers a kinematic region where t-channel exchange mechanisms play a dominant role. Access to this low momentum transfer region also allows the investigation of degrees of freedom not derived from constituent quark models, for example, the role of (vector) meson - baryon interactions and dynamically generated states in photoproduction reactions. Data taking for the first part of an extensive physics programme is complete and preliminary results and ongoing analysis are presented. (Less)

The first measurements of the beam-target-helicity-asymmetries $E$ and $G$ in the photoproduction of $\omega$-mesons off protons at the CBELSA/TAPS experiment are reported. $E$ ($G$) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. $E$ was measured over the photon energy range from close to threshold ($E_\gamma = 1108$~MeV) to $E_\gamma = 2300$~MeV and $G$ at a single energy interval of $1108 < E_\gamma, Comment: 6 pages, 6 figures

Photoproduction of two neutral pions off the proton is studied using linearly polarized photons, and the polarization observables I-s and I-c are measured for the first time. These two observables are unique to multi-meson final states; they characterize correlations between the linear photon polarization and the direction of outgoing single particles in photoproduction of three-body final states. The I-s and I-c distributions suggest that, in the 1.8 to 2.0 GeV mass region, the N(1520) 3/2(-)pi intermediate state is reached with reaction dynamics consistent with a dominant J(P) = 3/2(+) wave. These data are included in the Bonn-Gatchina (BnGa) partial wave analysis which is based on a large variety of data; the analysis confirms a significant contribution from the reaction chain gamma p -> N(1900)3/2(+) -> N(1520)3/2(-)pi(0) -> p pi(0)pi(0). (C) 2015 The Authors. Published by Elsevier B.V.

The reaction γ p → K S 0 Σ + is studied in the photon energy range from threshold. Linearly polarised photon beams from coherent bremsstrahlung enabled the first measurement of photon beam asymmetries in this reaction up to E γ = 1650 MeV . In addition, the recoil hyperon polarisation was determined through the asymmetry in the weak decay Σ + → p π 0 up to E γ = 2250 MeV . The data are compared to partial wave analyses, and the possible impact on the interpretation of a recently observed prominent structure in the cross section near the K ⁎ thresholds is discussed.

The analysis of high-precision ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}p$ cross-sectional data from the EPECUR Collaboration based on the multichannel $K$-matrix approach is presented. The sharp structures seen in these data are studied in terms of both opening thresholds and new resonance contributions. Some prominent features are found to be due to the opening $K\mathrm{\ensuremath{\Sigma}}$ channel. However, a complete description of the data is improved with the addition of two narrow resonant structures at $W\ensuremath{\sim}1.686$ and $W\ensuremath{\sim}1.720\phantom{\rule{4.pt}{0ex}}\mathrm{GeV}$. These structures are interpreted as manifestations of ${S}_{11}$ and ${P}_{11}$ resonances. The underlying nature of the observed phenomena is discussed.

The new BGO-OD experiment at the electron accelerator ELSA, of the University of Bonn, is designed to study the reaction dynamics of nucleon excitations in meson photoproduction. It consists of a central BGO calorimeter with a magnetic spectrometer in forward direction. The physics programme includes the measurement of polarisation observables using linearly and circularly polarised photon beams. Linear polarisation is obtained by coherent bremsstrahlung off a diamond crystal, and circular polarisation is obtained via bremsstrahlung from longitudinally polarised electrons. The degree of linear polarisation is determined from the bremsstrahlung spectrum itself. To determine the polarisation of the circularly polarised photon beam, the polarisation of the electron beam is measured by a Moller polarimeter. As a preliminary consistency check, the (linear) polarisation observable, Σ, was compared to world data for π^0 and η photoproduction. To determine the degree of circular polarisation, a Moller polarimeter was setup and first measurements of the electron beam polarisation performed.

BGO-OD is a new meson photoproduction experiment at the ELSA facility of Bonn University. It aims at the investigation of non strange and strange baryon excitations, and is especially designed to be able to detect weekly bound meson-baryon type structures. The setup for the BGO-OD experiment is presented, the characteristics of the photon beam and the detector performances are shown and the initial experimental program is discussed.

BGO-OD is a newly commissioned experiment to investigate the internal structure of the nucleon, using an energy tagged bremsstrahlung photon beam at the ELSA electron facility. The setup consists of a highly segmented BGO calorimeter surrounding the target, with a particle tracking magnetic spectrometer at forward angles. BGO-OD is ideal for investigating meson photoproduction. The extensive physics programme for open strangeness photoproduction is introduced, and preliminary analysis presented., 6 pages, 4 figures. Proceedings for the 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015)

Differential and total cross sections for eta-meson production in the reaction π−p → ηn were measured within the experimental program eta-meson physics implemented in the pion channel of the synchrocyclotron of the Petersburg Nuclear Physics Institute (PNPI, Gatchina). These measurements were performed at incident-pion momenta (700, 710, 720, and 730 MeV/c) in the vicinity of the threshold for the process under study by using the neutral-meson spectrometer designed and created at the Meson Physics Laboratory of PNPI. It is shown that, in the immediate vicinity of the threshold (685 MeV/c), the process of eta-meson production proceeds predominantly via S11(1535)-resonance formation followed by the decay S11(1535) → ηn (the respective branching fraction is Br ≈ 60%), but that, as the momentum of incident pions increases, the role of the D wave becomes ever more important. A detailed analysis of this effect indicates that it is due to the increasing contribution of the D13(1520) resonance. Although the branching fraction of the decay of this resonance through the ηn channel is assumed to be very small (BR ≈ 0.24%), the effect is enhanced owing to the interference between the D wave and the dominant resonance S11(1535).

The γ + p → K 0 + Σ + photoproduction reaction is investigated in the energy region from threshold to E γ = 2250 MeV . The differential cross section exhibits increasing forward-peaking with energy, but only up to the K ⁎ threshold. Beyond, it suddenly returns to a flat distribution with the forward cross section dropping by a factor of four. In the total cross section a pronounced structure is observed between the K ⁎ Λ and K ⁎ Σ thresholds.

The photoproduction of η ′ -mesons off different nuclei has been measured with the CBELSA/TAPS detector system for incident photon energies between 1500–2200 MeV. The transparency ratio has been deduced and compared to theoretical calculations describing the propagation of η ′ -mesons in nuclei. The comparison indicates a width of the η ′ -meson of the order of Γ = 15 – 25 MeV at ρ = ρ 0 for an average momentum p η ′ = 1050 MeV / c , at which the η ′ -meson is produced in the nuclear rest frame. The inelastic η ′ N cross section is estimated to be 3–10 mb. Parameterizing the photoproduction cross section of η ′ -mesons by σ ( A ) = σ 0 A α , a value of α = 0.84 ± 0.03 has been deduced.

The polarization observable I^s, a feature exclusive to the acoplanar kinematics of multi-meson final states produced via linearly polarized photons, has been measured for the first time. Results for the reaction g p -> p pi0 eta are presented for incoming photon energies between 970 MeV and 1650 MeV along with the beam asymmetry I^c. The comparably large asymmetries demonstrate a high sensitivity of I^s to the dynamics of the reaction. Fits using Bonn-Gatchina partial wave analysis demonstrate that the new polarization observables carry significant information on the contributing partial waves., 11 pages, 6 figures, v2 to appear in Phys. Lett. B

The differential cross-sections (DCS) of the η-production reaction π − p → ηn are measured at momenta of incident π − mesons (700, 710 and 720MeV/c) close to the threshold of this reaction. The experiment is carried out at the pion channel of the PNPI synchrocyclotron (with the momentum spread of the pion beam equal to 1.5%) using the Neutral Meson Spectrometer (NMS) designed and created at the Meson Physics Laboratory for detecting two photons from the decay η → 2γ. This spectrometer consisting of two electromagnetic total absorption calorimeter (24 CsI(Na) crystals in each calorimeter) allowed to obtain the DCS in the whole angular range from 0° to 180° in the c.m.s. It is shown that at 700MeV/c the DCS angular dependence is isotropic, indicating on the S-wave character of the η-production process while at higher momenta a significant contribution of the D-wave has led to the anisotropic angular dependence having a bowl-like shape.

Decays of baryon resonances in the second and the third resonance region into N pi(0)pi(0) are studied by photoproduction of two neutral pions off protons. Partial decay widths of N* and Delta* resonances decaying into Delta(1232)pi, N(pi pi)(S), N(1440)P-11 pi, and N(1520)D-13 pi are determined in a partial wave analysis of this data and of data from other reactions. Several partial decay widths were not known before. Interesting decay patterns are observed which are not even qualitatively reproduced by quark model calculations. In the second resonance region, decays into Delta(1232)pi dominate clearly. The N(pi pi)(S)-wave provides a significant contribution to the cross section, especially in the third resonance region. The P-13(1720) properties found here are at clear variance to PDG values. (c) 2007 Elsevier B.V. All rights reserved.

The photoproduction of 2π$^{0}$ mesons off protons was studied with the Crystal Barrel/TAPS experiment at the electron accelerator ELSA in Bonn. The energy of photons produced in a radiator was tagged in the energy range from 600 MeV to 2.5 GeV. Differential and total cross sections and pπ$^{0}$ π$^{0}$ Dalitz plots are presented. Part of the data was taken with a diamond radiator producing linearly polarized photons, and beam asymmetries were derived. Properties of nucleon and Δ resonances contributing to the pπ$^{0}$ π$^{0}$ final state were determined within the Bonn-Gatchina (BnGa) partial-wave analysis. The data presented here allow us to determine branching ratios of nucleon and Δ resonances for their decays into pπ$^{0}$ π$^{0}$ via several intermediate states. Most prominent are decays proceeding via Δ(1232)π, N(1440)1/2$^{+}$ π, N(1520)3/2$^{−}$ π, N(1680)5/2$^{+}$ π, but also pf$_{0}$(500), pf$_{0}$(980), and pf$_{2}$(1270) contribute to the reaction.

The photoproduction of 2$\pi^0$ mesons off protons was studied with the Crystal Barrel/TAPS experiment at the electron accelerator ELSA in Bonn. The energy of photons produced in a radiator was tagged in the energy range from 600\,MeV to 2.5\,GeV. Differential and total cross sections and $p\pi^0\pi^0$ Dalitz plots are presented. Part of the data was taken with a diamond radiator producing linearly polarized photons, and beam asymmetries were derived. Properties of nucleon and $\Delta$ resonances contributing to the $p\pi^0\pi^0$ final state were determined within the BnGa partial wave analysis. The data presented here allow us to determine branching ratios of nucleon and $\Delta$ resonances for their decays into $p\pi^0\pi^0$ via several intermediate states. Most prominent are decays proceeding via $\Delta(1232)\pi$, $N(1440)1/2^+\pi$, $N(1520)3/2^-\pi$, $N(1680)5/2^+\pi$, but also $pf_0(500)$, $pf_0(980)$, and $pf_2(1270)$ contribute to the reaction.

The N pi(0)pi(0) decays of positive-parity N* and Delta* resonances at about 2 GeV are studied at ELSA by photoproduction of two neutral pions off protons. The data reveal clear evidence for several intermediate resonances: Delta(1232), N(1520)3/2(-), and N(1680)5/2(+), with spin parities J(P) = 3/2(+), 3/2(-), and 5/2(+). The partial wave analysis (within the Bonn-Gatchina approach) identifies N(1440)1/2(+) and the N(pi pi)s (wave) (abbreviated as N sigma here) as further isobars and assigns the final states to the formation of nucleon and Delta resonances and to nonresonant contributions. We observe the know Delta(1232)pi decays of Delta(1910)1/2(+), Delta(1920)3/2(+), Delta(1905)5/2(+), Delta(1950)7/2(+), and of the corresponding spin-parity series in the nucleon sector, N(1880)1/2(+), N(1900)3/2(+), N(2000)5/2(+), and N(1990)7/2(+). For the nucleon resonances, these decay modes are reported here for the first time. Further new decay modes proceed via N(1440)1/2(pi)(+), N(1520)3/2(pi)(-) , N(1680)5/2(pi)(+), and N sigma. The latter decay modes are observed in the decay of N* resonances and at most weakly in Delta(*) decays. It is argued that these decay modes provide evidence for a 3-quark nature of N* resonances rather than a quark-diquark structure.

Omega photoproduction off hydrogen and deuterium has been studied with the tagged photon beam of the ELSA accelerator in Bonn for photon energies up to 2.0 GeV. The omega meson has been identified via the omega -> pi(0) gamma -> gamma gamma gamma decay mode, using the combined setup of the Crystal Barrel/TAPS detector systems. Both inclusive and exclusive analyses have been carried out. Differential and total cross-sections have been derived for omega mesons produced off free protons and off protons and neutrons bound in deuterium. The cross-section for the production off the bound neutron is found to be a factor of a parts per thousand 1.3 larger than the one off the bound proton in the incident beam energy region 1.2 GeV

New experimental data that were obtained by the PNPI-ITEP Collaboration have resolved some discrete ambiguities in the partial-wave analysis (PWA). These results were used in the new FA02 PWA performed at George Washington University. At the same time, the FA02 PWA has revealed considerable fewer N* and Δ resonances than those listed in the RPP tables. This circumstance aggravated the known problem of so-called missing resonances. The program for further measurements of the spin rotation parameters in elastic πN scattering that are required to eliminate the remaining discrete PWA ambiguities is discussed.

A program of measurement of the polarization parameter P in elastic {pi}{sup +}p interaction in the resonance region of backward pion scattering is presented. This program is aimed at determining the bifurcation points of the trajectory of zeros of the pion-nucleon amplitude and, hence, at unambiguously reconstructing the amplitude of {pi}N scattering in the second resonance region. It is planned to perform a relevant experiment in a pion beam from the accelerator of the Institute of Experimental and Theoretical Physics (ITEP, Moscow)

The SPIN-P experimental setup was designed for measuring the P asymmetry during pion scattering into the backward hemisphere at a minimum differential cross section of elastic πpscattering. The physical grounds of the experiment and the results of its simulation by the Monte Carlo method are presented. The setup is composed of a polarized proton target in a superconducting solenoid with vertical polarization of free protons, wire track detectors, scintillation counters, electronics for data readout and processing, and an appropriate computer network. The experimental program has been under way since 2002 on the pion beam of the proton synchrotron at the Institute of Theoretical and Experimental Physics (Moscow).

Experimental data on the spin-rotation parameters A and R in elasticπ+p interaction were obtained for the first time at a momentum of pπ = 1.62 GeV/c. These data are necessary for unambiguously reconstructing the amplitude of pion-nucleon scattering and, hence, for deducing a correct spectrum of nonstrange baryon resonances. In order to obtain results for the polarization parameters A and R with the minimum possible systematic error, the carbon polarimeter used was preliminarily calibrated in a dedicated experiment; that is, the analyzing power was measured in proton-carbon scattering for incidentproton energies in the range Tp=0.7–1.3 GeV. The experimental data reported in the present article were obtained by a collaboration of researchers from the Petersburg Nuclear Physics Institute and Institute of Theoretical and Experimental Physics (ITEP, Moscow) at the ITEP synchrotron.

Differential cross sections for the reaction π−p → π0n were measured for nearly forward scattering angles. The experiment was performed at the pion channel of the synchrocyclotron installed at the Petersburg Nuclear Physics Institute (PNPI, Gatchina), the incident-pion momenta ranging between 417 and 710 MeV/c. The measurements, which involved recording both photons from the decay process π0 → 2γ, employed the neutral-pion spectrometer developed at the PNPI. A description of the experimental facility is given, and the results of the measurements are presented.

The spin rotation parameters A and R were measured for the elastic pion-proton scattering by the PNPI-ITEP collaboration in the D13 (1700), ΔS31(1900), ΔP33(1920) and ΔD33 (1940) resonances region. These resonances were absent in the set of partial wave analysis (PWA) of the Virginia Polytechnic Institute group (VPI), but was included in the tables of the Review of Particle Physics. The main goal of the experimental program was to resolve the current PWA’s disagreement in spin rotation parameters value predictions. Simultaneously with A and R the polarization parameter P was measured with the purpose to improve the experimental data base and estimate the experimental systematic errors. Our results for spin rotation parameters A and |R| are in agreement with PWA VPI predictions.

New experimental data on the spin-rotation parameters A and R measured for elastic π ± p scattering in the resonance region and on the asymmetry in pC scattering at primary momenta in the range 1.35–2.02 GeV/c, as well as in quasielastic proton scattering on nuclei in the same momentum range, are summarized. All these data were recently obtained by using the proton synchrotron installed at the Institute of Theoretical and Experimental Physics (ITEP, Moscow). The spectrum and features of seven isospin-3/2 baryon resonances that form a peak in the total cross section at a c.m. energy of 1.9 GeV are analyzed on the basis of new data on the parameters A and R, and the results of this analysis are presented. The experiments surveyed in this article were performed by a collaboration of researchers from ITEP and the Petersburg Nuclear Physics Institute (PNPI, Gatchina), the ITEP-PNPI collaboration.

The Nπ^{0}π^{0} decays of positive-parity N^{*} and Δ^{*} resonances at about 2 GeV are studied at ELSA by photoproduction of two neutral pions off protons. The data reveal clear evidence for several intermediate resonances: Δ(1232), N(1520)3/2^{-}, and N(1680)5/2^{+}, with spin parities J^{P}=3/2^{+}, 3/2^{-}, and 5/2^{+}. The partial wave analysis (within the Bonn-Gatchina approach) identifies N(1440)1/2^{+} and the N(ππ)_{S wave} (abbreviated as Nσ here) as further isobars and assigns the final states to the formation of nucleon and Δ resonances and to nonresonant contributions. We observe the known Δ(1232)π decays of Δ(1910)1/2^{+}, Δ(1920)3/2^{+}, Δ(1905)5/2^{+}, Δ(1950)7/2^{+}, and of the corresponding spin-parity series in the nucleon sector, N(1880)1/2^{+}, N(1900)3/2^{+}, N(2000)5/2^{+}, and N(1990)7/2^{+}. For the nucleon resonances, these decay modes are reported here for the first time. Further new decay modes proceed via N(1440)1/2^{+}π, N(1520)3/2^{-}π, N(1680)5/2^{+}π, and Nσ. The latter decay modes are observed in the decay of N^{*} resonances and at most weakly in Δ^{*} decays. It is argued that these decay modes provide evidence for a 3-quark nature of N^{*} resonances rather than a quark-diquark structure.

Photoproduction off protons of the pπ 0 η three-body final state was studied with the Crystal Barrel/TAPS detector, at the electron stretcher accelerator ELSA in Bonn, for incident energies from the π 0 η production threshold up to 2.5 GeV. Differential cross sections and the total cross sections are presented. The use of linearly polarized photons gives access to the polarization observables Σ, I s , and I c , the latter two characterize beam asymmetries in case of three-body final states. Δ(1232)η, N(1535)1/2− π, and pa 0(980) are the dominant isobars contributing to the reaction. The partial wave analysis confirms the existence of some nucleon and Δ resonances, for which so far only fair evidence was reported. A large number of decay modes of known nucleon and Δ resonances is presented. It is shown that detailed investigations of decay branching ratios may provide a key to unravelling the structure of nucleon and Δ resonances.

The spin rotation parameters A and R were measured for the elastic pion-proton scattering by the PNPI-ITEP collaboration in the D13(1700) resonance region. The main goal of the experimental program is to resolve the current partial-wave analyses (PWA) uncertainties. Simultaneously with A and R the polarization parameter P was measured with the purpose to improve the experimental database and estimate systematic errors. The constraint which demands a smooth energy dependence of all π-p transverse amplitude zeros in the complex plane together with the new experimental data on A parameter can lead to the conclusion that the Barrelet branch of “zero trajectories" is chosen improperly in PWA of the Carnegie-Mellon-Lawrence-Berkely-Laboratory groups at the range of the pion beam momentum near 1.0 GeV/c. The setup included a longitudinally polarized proton target with superconductive magnet, multiwire spark chambers and carbon polarimeter with thick filter. The experiment was performed at the ITEP proton synchrotron, Moscow.