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تسجيل مستخدم جديدMedium Effects in Kaon and Antikaon Production in Nuclear Collisions at Subthreshold Beam Energies
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Production cross sections of K$^+$ and K$^-$ mesons have been measured in C+C collisions at beam energies per nucleon below and near the nucleon-nucleon threshold. At a given beam energy, the spectral slopes of the K$^-$ mesons are significantly steeper than the ones of the K$^+$ mesons. The excitation functions for K$^+$ and K$^-$ mesons nearly coincide when correcting for the threshold energy. In contrast, the K$^+$ yield exceeds the K$^-$ yield by a factor of about 100 in proton-proton collisions at beam energies near the respective nucleon-nucleon thresholds.
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Differential production cross sections of K$^-$ and K$^+$ mesons have been measured as function of the polar emission angle in Ni+Ni collisions at a beam energy of 1.93 AGeV. In near-central collisions, the spectral shapes and the widths of the rapid
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and as a function of impact parameter but the slopes of K+ and K- spectra differ for all impact parameters. Furthermore the respective polar angle distributions will be presented as a function of centrality.
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The relativistic transport model, in which the nucleon effective mass is connected to the scalar field while its energy is shifted by the vector potential, is extended to include the kaon degree of freedom. We further take into account the medium mod
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