On the K^+_- meson production from the quark-gluon plasma phase in ultra-relativistic heavy-ion collisions

Abstract

An abundance of the strangeness that can be induced in a thermalized quark-gluon plasma (QGP) is considered as a signal of the QGP phase appearing in the intermediate state of ultra-relativistic heavy-ion collisions. As a quantitative characteristic of this signal we take the ratio R_{K^+ K^-} = N_{K^+}/N_{K^-} of the multiplicities of the production of K^+_- mesons. This ratio is evaluated for a thermalized QGP phase of QCD and for the quark-gluon system escaped from the QGP phase. For a thermalized QGP phase the ratio R_{K^+ K^-} has been found as a smooth function of a 3-momentum of the K^+_- mesons and a temperature ranging the values from the region 160 MeV < T <200 MeV. We show that at the temperature T= 175 MeV our prediction for the ratio R_{K^+K^-}(q,T = 175) = 1.80^{+ 0.04}_{-0.18} agrees good with the experimental data of NA49 and NA44 Collaborations on central ultra-relativistic Pb-Pb collisions at 158 GeV per nucleon: R^{\exp}_{K^+K^-} = 1.80\pm 0.10. For the ratio of the K^+ and \pi^+ multiplicities we have obtained the value R_{K^+\pi^+}(q,T = 175) = 0.134\pm 0.014 agreeing good with the experimental data of NA35 Collaboration on the nucleus-nucleus collisions at 200 GeV per nucleon R^{\exp}_{K^+\pi^+} = 0.137\pm 0.008.