Phi meson production is studied by the NA49 collaboration in central Pb+Pb collisions at 20A, 30A, 40A, 80A and 158A GeV beam energy. The data are compared to measurements at lower and higher energies and to microscopic and thermal models. The energy dependence of yields and spectral distributions is compatible with the assumption that partonic degrees of freedom set in at low SPS energies.
PHI transverse momentum spectra at incident energy 20 GeV/nucleon integrated over the rapidity range 0 to 1.8.
PHI transverse momentum spectra at incident energy 30 GeV/nucleon integrated over the rapidity range 0 to 1.8.
PHI transverse momentum spectra at incident energy 40 GeV/nucleon integrated over the rapidity range 0 to 1.5.
Results on charged pion and kaon production in central Pb+Pb collisions at 20A and 30A GeV are presented and compared to data at lower and higher energies. A rapid change of the energy dependence is observed around 30A GeV for the yields of pions and kaons as well as for the shape of the transverse mass spectra. The change is compatible with the prediction that the threshold for production of a state of deconfined matter at the early stage of the collisions is located at low SPS energies.
Transverse mass spectra for pion production in the central rapidity region for collisions at 20 GeV per nucleon.
Transverse mass spectra for pion production in the central rapidity region for collisions at 30 GeV per nucleon.
Transverse mass spectra for kaon production in the central rapidity region for collisions at 20 GeV per nucleon.
Quasiexclusive neutral meson production in pN-interactions is studied in experiments with the SPHINX facility operating in a proton beam from the IHEP accelerator (Ep=70 GeV). The cross sections and the parameters of the differential distributions for πo, ω, η and Ko production in the deep fragmentation region (xF > 0.79 ÷ 0.86) are presented. The results show that such proton quasiexclusive reactions with baryon exchange may be promising in searches for exotic mesons.
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Data on the graph only.
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FOR -T = 0.002 TO 0.05 GEV**2.
The differential cross-sections in the range of four momentum transfer squared from 0.003 to 0.120 (GeV c) 2 were measured at 30, 50 and 70 GeV by using a thin polyethilene target in the internal proton beam of the Serpukhov accelerator. The slope parameter, the ratio of the real to the imaginary part of the forward amplitude and the cross-section in the diffraction cone were measured.
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ASSUMING UNIFORM SLOPE.