We report on measurements of the differential cross section $d\ensuremath{\sigma}/d\mathrm{\ensuremath{\Omega}}$ in the energy region of $\sqrt{s}=2.5$--$2.9\phantom{\rule{0.16em}{0ex}}\mathrm{GeV}$ of the reaction $pp\ensuremath{\rightarrow}{{pp}}_{s}{\ensuremath{\pi}}^{0}$, where ${{pp}}_{s}$ is a $^{1}S_{0}$ proton pair. The experiment has been performed with the ANKE spectrometer at COSY-J\"ulich. The data reveal a peak in the energy dependence of the forward ${{pp}}_{s}$ differential cross section at the energy $\sqrt{s}=2.65\phantom{\rule{0.16em}{0ex}}\mathrm{GeV}$ with the width $\mathrm{\ensuremath{\Gamma}}=0.26\phantom{\rule{0.16em}{0ex}}\mathrm{GeV}$, and also the cross section slope changes its sign in the region of the observed peak. This is an indication for the excitation of a new $D(2650)$ resonant state, that may be a dibaryon resonance system consisting of two excited baryons $\mathrm{\ensuremath{\Delta}}(1232)$ and ${N}^{*}(1440)$.

We report on measurements of the differential cross section du/dS2 in the energy region of .,/s = 2.5-2.9 GeV of the reaction pp -> {pp}s pi 0, where {pp}s is a 1S0 proton pair. The experiment has been performed with the ANKE spectrometer at COSY-Julich. The data reveal a peak in the energy dependence of the forward {pp}s differential cross section at the energy .,/s = 2.65 GeV with the width I' = 0.26 GeV, and also the cross section slope changes its sign in the region of the observed peak. This is an indication for the excitation of a new D(2650) resonant state, that may be a dibaryon resonance system consisting of two excited baryons Delta(1232)

We report on measurements of the differential cross section dσ/dΩ in the energy region of √(s) = 2.5-2.9 GeV of the reaction pp →{pp}_s π^0 where {pp}_s is a ^1S_0 proton pair. The experiment has been performed with the ANKE spectrometer at COSY-Jülich. The data reveal a peak in the energy dependence of the forward {pp}_s differential cross section at the energy √(s) = 2.65 GeV with the width Γ = 0.26 GeV, and also the cross section slope changes its sign in the region of the observed peak. This is an indication for the excitation of a new D(2650) resonant state, that may be a dibaryon resonance system consisting of two excited baryons Δ(1232) and N^*(1440).

The reaction pp → {pp} s p 0 , where {pp}s denotes a diproton, i.e. an unbound interacting proton pair in the 1 S 0 , state, was investigated in order to obtain a differential cross section ds/dW at small angles in the energy range 1.6–2.4 GeV. This work is intended for the presentation of the main procedures in the processing of experimental data.

The pp -> {pp}(s)pi(0), where {pp}(s) reaction is an unbound interacting proton pair in the S-1(0) final state, was investigated at small angles in the beam energy range of T-beam = 1.5-2.5 GeV. For the pp -> {pp}(s)pi(0) reaction, we obtained the angular dependences of the differential cross section d sigma/d Omega at forward angles for several energies, the energy dependences of the cross section at zero angle d sigma/d Omega (0) and angular slope k of the forward cross section. The obtained results confirm the existence of a second peak in the d sigma/d Omega (0) energy dependence for the pp -> {pp}(s)pi(0) reaction and allow to estimate its maximum, mass, and width. The change in the sign of the slope k in comparison with the region of the first peak indicates a change in the reaction dynamics at the energies of root s approximate to 2.3-2.6 GeV.

Nucleon–nucleon collisions with impact-parameter values below the nucleon quark-core radius are considered and experimental signatures for selecting such central collisions are formulated.

A process of inelastic nucleon-nucleon collisions with the impact parameter less than a radius of the nucleon quark core is considered. The criteria for selection of such collisions from a full array of the nucleon-nucleon interactions are suggested.

Kinematic filtting is one of the popular particle physics problems where constraint minimization is used. The constraints setting additional relations between parameters p can be given in form of equations φ(p1,..., pn) = 0. Often these equations are non-linear and complicated, and thus it is impossible or impractical to eliminate redundant parameters directly. The article covers employing of the minimization approach called a method of elimination of differentials, that is being developed at JINR as an extension to the FUMILI minimizer, and is intended for kinematic filtting in particle physics experiments.

The recent results of dibaryon studies at ANKE are being presented, along with our plans concerning further studies on the topic. The D03 resonance has been observed at ANKE in the coherent pd → pd+(ππ)0 channel, accompanied by the ABC effect. An explanation of the ABC effect has been proposed, suggesting to to explain it as a kinematic cumulation of the pion pairs in the D03 → D12 + π → d + (π + π)I=0 cascade decay channel due to the predominantly collinear D12 decay. Based on this hypothesis, a search for a D21 signal in the pp → {pp}sππ reaction is suggested. The p-wave dibaryon resonances 3P2 and 3P0 have been observed at ANKE; for 3P0 it is a first experimental observation. Preliminary results for a resonance peak in the pp → {pp}sπ0 reaction with the mass m = 2646 ± 5 MeV and the width Γ = 132 ± 14 MeV are being presented. Also we propose to search for the narrow NN*(1535) resonance in the pd → pdη reaction.

The pp → {pp}sπ0 reaction, where {pp}s denotes a diproton, i.e. an unbound interacting proton pair in the 1S0 state, has been studied in order to obtain the forward differential cross section dσ/dΩ at 11 energy values in the region of 0.8–2.8 GeV. A resonance-like peak with the energy E0 = 2.647 ± 0.005 GeV and the width Γ = 0.26 ± 0.03 GeV has been observed in the energy dependence of the differential cross section dσ/dΩ at zero angle. The slope of the angular dependence for the energies in the peak region is different compared with the energies around it. Possible implications on this phenomenon are discussed.

The pp -> {pp}(s)pi(0) reaction, where {pp}(s) denotes a diproton, i.e. an unbound interacting proton pair in the S-1(0) state, has been studied in order to obtain the forward differential cross section d sigma/d Omega at 11 energy values in the region of 0.8-2.8 GeV. A resonance-like peak with the energy E-0 = 2.647 +/- 0.005 GeV and the width Gamma = 0.26 +/- 0.03 GeV has been observed in the energy dependence of the differential cross section d sigma/d Omega at zero angle. The slope of the angular dependence for the energies in the peak region is different compared with the energies around it. Possible implications on this phenomenon are discussed.

The pp → {pp}sπ0 reaction, where {pp}s denotes a diproton, i.e. an unbound interacting proton pair in the 1S0 state, has been studied in order to obtain the forward differential cross section dσ/dΩ at 11 energy values in the region of 0.8–2.8 GeV. A resonance-like peak with the energy E0 = 2.647 ± 0.005 GeV and the width Γ = 0.26 ± 0.03 GeV has been observed in the energy dependence of the differential cross section dσ/dΩ at zero angle. The slope of the angular dependence for the energies in the peak region is different compared with the energies around it. Possible implications on this phenomenon are discussed.

The vector (Ayd) and tensor (Axx and Ayy) analysing powers in deuteron–proton elastic scattering have been measured in the forward hemisphere at deuteron kinetic energies of Td=1.2 GeV and 2.27 GeV using the ANKE spectrometer at the COSY storage ring. The results are compared with other experimental data and with predictions made within the framework of Glauber multiple scattering theory.

. The reaction p + d → p + d + X was studied at 0.8-2.0 GeV proton beam energies with the ANKE magnetic spectrometer at the COSY synchrotron storage ring. The proton-deuteron pairs emerging with high momenta, 0.6-1.8 GeV/ c , were detected at small angles with respect to the proton beam. Distribution over the reaction missing mass M_x reveals a local enhancement near the threshold of the pion pair production specific for the so-called ABC effect. The enhancement has a structure of a narrow bump placed above a smooth continuum. The invariant mass of the dππ system in this enhancement region exhibits a resonance-like peak at M_dππ≈ 2.36 GeV/ c 2 with the width Γ≈ 0.10 GeV/ c 2 . A possible interpretation of these features is discussed.

The analyzing powers in proton-deuteron elastic and proton-neutron quasi-elastic scattering have been measured at small angles using a polarized proton beam at the COSY storage ring incident on an unpolarized deuterium target. The data were taken at 796MeV and five higher energies from 1600MeV to 2400MeV. The analyzing power in pd elastic scattering was studied by detecting the low energy recoil deuteron in telescopes placed symmetrically in the COSY plane to the left and right of the beam whereas for pn quasi-elastic scattering a low energy proton was registered in one of the telescopes in coincidence with a fast scattered proton measured in the ANKE magnetic spectrometer. Though the experiment explores new domains, the results are consistent with the limited published information.

Values of the proton analysing power in the pd -> He-3 pi(0)/H-3 pi(+) reactions at 350-360MeV per nucleon were obtained by using a polarised proton beam incident on a deuterium cluster-jet target and with a polarised deuteron beam incident on a target cell filled with polarised hydrogen. These results have a much larger angular coverage than existing data. First measurements are also presented of the deuteron vector analysing power and the deuteron-proton spin correlations. Data were also obtained on the deuteron-proton spin correlation and proton analysing power at small angles at 600 MeV per nucleon, though the angular coverage at this energy was much more restricted even when using a deuteron beam. By combining the extrapolated values of the spin correlations to the forward or backward directions with published measurements of the deuteron tensor analysing powers, the relative phases between the two non-vanishing amplitudes were evaluated. (C) 2016 The Authors. Published by Elsevier B.V.

We report on measurements of the differential cross section d sigma/d Omega and the first measurement of the analyzing power A(y) in the Delta(1232) excitation energy region of the reaction pp -> {pp}(s)pi(0) where {pp}(s) is a S-1(0) proton pair. The experiment has been performed with the ANKE spectrometer at COSY-Julich. The data reveal a peak in the energy dependence of the forward {pp}(s) differential cross section, a minimum at zero degrees of its angular distribution, and a large analyzing power. The results present a direct manifestation of two two-baryon resonance-like states with J(P) = 2(-) and 0(-) and an invariant mass of 2.2 GeV/c(2).

The differential cross section for proton–proton elastic scattering has been measured at a beam kinetic energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV for centre-of-mass angles in the range from 12°–16° to 25°–30°, depending on the energy. A precision in the overall normalisation of typically 3% was achieved by studying the energy losses of the circulating beam of the COSY storage ring as it passed repeatedly through the windowless hydrogen target of the ANKE magnetic spectrometer. It is shown that the data have a significant impact upon the results of a partial wave analysis. After extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations.