Hartnack Ch, Oeschler H, Aichelin J
SUBATECH, Laboratoire de Physique Subatomique et des Technologies Associées, University of Nantes-IN2P3/CNRS-Ecole des Mines de Nantes, 4 rue Alfred Kastler, F-44072 Nantes, Cedex 03, France.
Phys Rev Lett. 2003 Mar 14;90(10):102302. doi: 10.1103/PhysRevLett.90.102302. Epub 2003 Mar 12.
In heavy ion reactions at energies around (1-2)A GeV the measured K- yields appear rather high as compared to pp collisions as shown by the KaoS Collaboration. Employing quantum molecular dy-namics simulations, we show that this is caused by the fact that the dominant production channel is not BB-->BBK+K- but the mesonic Lambda(Sigma)pi-->K-B reaction. Because the Lambda (Sigma) stem from the reaction BB-->Lambda(Sigma)K+B, the K+ and the K- yield are strongly correlated, i.e., the K(-)/K(+) ratio occurs to be nearly independent of the impact parameter as found experimentally. The final K- yield is strongly influenced by the K+N [due to their production via the Lambda(Sigma)] but very little by the K-N potential.
在能量约为（1 - 2）A GeV的重离子反应中，正如KaoS合作组所展示的，与质子 - 质子碰撞相比，测得的K⁻产额显得相当高。通过量子分子动力学模拟，我们表明这是由于主导产生通道不是BB→BBK⁺K⁻，而是介子Λ（Σ）π→K⁻B反应。因为Λ（Σ）源于反应BB→Λ（Σ）K⁺B，所以K⁺和K⁻产额紧密相关，即实验发现K⁻/K⁺比值几乎与碰撞参数无关。最终的K⁻产额受K⁺N（由于它们通过Λ（Σ）产生）的强烈影响，但受K⁻N势的影响很小。
