First measurement of antikaon phase-space distributions in nucleus–nucleus collisions at subthreshold beam energies

Autor: F. Uhlig, G. Surówka, H. Stroebele, Andreas Wagner, I. Boettcher, Y. Shin, F. Puehlhofer, E. Schwab, A. Foerster, P. Koczon, B. Kohlmeyer, E. Grosse, C. Sturm, F. Laue, L. Naumann, F. Dohrmann, M. Menzel, M. Debowski, W. Walus, Peter Senger, H. Oeschler
Rok vydání: 2000
Předmět:
Zdroj: Physics Letters B, 495 (2000) 26-32
ISSN: 0370-2693
Popis: 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.
16 pages, 3 figures, accepted for publication in Physics Letters B
Databáze: OpenAIRE
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