Probing the Quark Gluon Plasma on the Yoctosecond Scale

In ultra-relativistic heavy ion collisions a fireball of hot and dense matter is created. When the energy density inside the fireball is very high, liberation of partons is expected to occur and a new phase of matter, the Quark Gluon Plasma (QGP) is formed. Short lived hadronic resonances are sensitive to the medium properties of a heavy-ion collision, in particular to the temperature, density and expansion velocity. Resonances decaying into hadrons are used to estimate the time span and hadronic interaction cross section in the hadronic phase between chemical and kinetic freeze-out. The detection of early decoupled resonances aims at studying chiral symmetry restoration via their mass shift and width broadening. This talk will summarize the results from LHC and RHIC energies.