Speaker
Description
Heavy-ion collisions allow to recreate conditions present in the universe shortly after the Big
Bang when the quark-gluon plasma can be formed. The properties of such plasma can be
studied using Upsilon mesons. Each of Upsilon states is expected to dissociate at a different
temperature reached in the plasma, through Debye-like screening of color charges. Thus, their
production yields are suppressed to different levels with respect to the yield in p+p collisions.
Additional cold nuclear matter effects can be studied in p+A or d+A collisions. Furthermore,
the production mechanism of these heavy mesons is not fully understood and this can be
studied in p+p collisions as well.
In this talk, we will present an overview of recent measurements on the production of Upsilon
states by the STAR experiment. These include a comprehensive study performed in Au+Au,
p+p, and p+Au collisions at p √s NN = 200 GeV as well as p+p collisions at √s = 500 GeV.
