Strangeness and causality constraint in heavy ion collision
(Physics and Astronomy Depart., Uni. Catania, Italy)
Sala PA1, IST, Pavilhão de Matemática
Wednesday, April 2nd, 2014 at 04:00 PM
The thermal multihadron production observed in different high energy
collisions poses many basic problems: why do even elementary, e+ e-;
and hadron-hadron, collisions show thermal behaviour? Why
is there in such interactions a suppression of strange particle
production? Why does the strangeness sup pression almost disappear in
relativistic heavy ion collisions? Why in these collisions is the
time less than ~ 0.5 fm/c?
The recently proposed mechanism of thermal hadron production through
Hawking-Unruh radiation can naturally answer the previous questions.
Indeed, the interpretation of quark-antiquark pairs production, by the
sequential string breaking, as tunneling through the event horizon of
confinement leads to thermal behavior with a universal temperature, T
~ 170 Mev,related to the quark acceleration, a, by T = a/2?.
The resulting temperature depends on the quark mass and then on the
content of the produced hadrons, causing a deviation from full equilibrium
and hence a suppression of strange particle production in elementary
collisions. In nucleus-nucleus collisions, where the quark density is much
bigger, one has to introduce an average temperature (acceleration) which
dilutes the quark mass effect and the strangeness suppression almost
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