Abstract:
The squeeze-out phenomenon of K + and K − mesons, i.e. the azimuthal asymmetry of K + and K − mesons emitted at midrapidity in heavy ion reactions, is investigated for beam energies of 1–2 A.GeV. It is found that the squeeze-out signal is strongly affected by in-medium potentials of these mesons. The repulsive K +-nucleus potential gives rise to a pronounced out-of-plane emission of K +'s at midrapidity. With the K + potential we reproduce well the experimental data of the K + azimuthal distribution. It is found that the attractive K −-nucleus potential cancels to a large extent the influence of rescattering and reabsorption of the K − mesons on the projectile and target residuals (i.e. shadowing). This results in an azimuthally isotropic emission of the midrapidity K − mesons with transverse momentum up to 0.8 GeV/c. Since it is well accepted that the shadowing alone would lead to a significant out-of-plane preference of particle emission, in particular at high transverse momenta, the disappearance of the out-of-plane preference for the K − mesons can serve as an unambiguous signal of the attractive K − potential. We also apply a covariant formalism of the kaon dynamics to the squeeze-out phenomenon. Discrepancies between the theory and the experiments and possible solutions are discussed.
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Received: 15 September 1998 / Revised version: 18 January 1999
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Wang, Z., Fuchs, C., Faessler, A. et al. Kaon squeeze-out in heavy ion reactions . EPJ A 5, 275–283 (1999). https://doi.org/10.1007/s100500050286
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DOI: https://doi.org/10.1007/s100500050286