PUB - Publikationen an der Universität Bielefeld

The thermal multihadron production observed in different high energycollisions poses many basic problems: why do even elementary, $e^+e^-$ andhadron-hadron, collisions show thermal behaviour? Why is there in suchinteractions a suppression of strange particle production? Why does thestrangeness suppression almost disappear in relativistic heavy ion collisions?Why in these collisions is the thermalization time less than $\simeq 0.5$ fm/c?We show that the recently proposed mechanism of thermal hadron productionthrough Hawking-Unruh radiation can naturally answer the previous questions.Indeed, the interpretation of quark- antiquark pairs production, by thesequential string breaking, as tunneling through the event horizon of colourconfinement leads to thermal behavior with a universal temperature, $T \simeq170$ Mev,related to the quark acceleration, a, by $T=a/2\pi$. The resultingtemperature depends on the quark mass and then on the content of the producedhadrons, causing a deviation from full equilibrium and hence a suppression ofstrange particle production in elementary collisions. In nucleus-nucleuscollisions, where the quark density is much bigger, one has to introduce anaverage temperature (acceleration) which dilutes the quark mass effect and thestrangeness suppression almost disappears.