First Measurement of Antikaon Phase-Space Distributions in Nucleus-Nucleus Collisions at Subthreshold Beam Energies

M. Menzel; I. Boettcher; M. Debowski; F. Dohrmann; A. Foerster; E. Grosse; P. Koczon; B. Kohlmeyer; F. Laue; L. Naumann; H. Oeschler; F. Puehlhofer; E. Schwab; P. Senger; Y. Shin; H. Stroebele; C. Sturm; G. Surowka; F. Uhlig; A. Wagner; W. Walus

doi:10.1016/s0370-2693(00)01232-6

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First Measurement of Antikaon Phase-Space Distributions in Nucleus-Nucleus Collisions at Subthreshold Beam Energies

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Abstract

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 rapidity distributions of K$^-$ and K$^+$ mesons are in agreement with the assumption of isotropic emission. In non-central collisions, the K$^-$ and K$^+$ rapidity distributions are broader than expected for a single thermal source. In this case, the polar angle distributions are strongly forward-backward peaked and the nonisotropic contribution to the total yield is about one third both for K$^+$ and K$^-$ mesons. The K$^-$/K$^+$ ratio is found to be about 0.03 independent of the centrality of the reaction. This value is significantly larger than predicted by microscopic transport calculations if in-medium modifications of K mesons are neglected.

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M. Menzel, I. Boettcher, M. Debowski, F. Dohrmann, A. Foerster, E. Grosse, P. Koczon, B. Kohlmeyer, F. Laue, L. Naumann, H. Oeschler, F. Puehlhofer, E. Schwab, P. Senger, Y. Shin, H. Stroebele, C. Sturm, G. Surowka, F. Uhlig, A. Wagner, W. Walus. 2000-10-23. First Measurement of Antikaon Phase-Space Distributions in Nucleus-Nucleus Collisions at Subthreshold Beam Energies. https://doi.org/10.1016/s0370-2693(00)01232-6

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