Publication : t19/121

Abstract:
We show that the mean transverse momentum of charged hadrons, ⟨pt⟩, in ultrarelativistic heavy-ion collisions is proportional the temperature of the quark-gluon plasma from which particles are emitted. We introduce an effective hydrodynamic description of the system created in a relativistic heavy-ion collision to relate experimental data on ⟨pt⟩ and charged-particle multiplicity to the thermodynamic properties of the quark-gluon plasma created in experiments. We find that Large Hadron Collider (LHC) data on Pb-Pb collisions at sNN−−−√=5.02 TeV is compatible with a deconfined medium with entropy density s=20±5~fm−3 and speed of sound c2s=0.24±0.04 at a temperature T=222±9~MeV, in agreement with lattice calculations. We identify the main sources of theoretical error in the extraction of these quantities from heavy-ion data.

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