Parton-medium cross section and average QGP viscosity in lead-lead collisions at LHC
Korotkikh, V. L. · Zabrodin, E. E.
Original · EN
The recent experimental CMS and E-by-E ATLAS data on the elliptic anisotropy of particles in collisions are used to extract parton medium cross-section and the quark-gluon plasma viscosity-to-entropy ratio within the incomplete equilibration medium model. Our method assumes extrapolation of the measured pseudorapidity spectrum of charged particles to low-pₜ range. Then the rapidity distribution of both charged and neutral hadrons is restored. The extracted value of the parton-medium cross section is found to be σ= (3.1 ± 0.2) mb. It yields η/s = 0.17 ± 0.02 for the ratio of shear viscosity to entropy density in QGP phase. The last result is in a good agreement with the estimates obtained by calculations within the viscous hydrodynamics.
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