HET-Discovery seminar by Anthony Timmims – University of Copenhagen

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HET-Discovery seminar by Anthony Timmims

Title: Experimental constraints on the temperature dependence of η/s
Abstract: Relativistic Heavy-Ion collisions at the Large Hadron Collider (LHC) are believed to create a state of matter called the Quark Gluon Plasma (QGP). In the QGP, nuclear matter "melts" and quarks and gluons become the relevant degrees of freedom. The development of anisotropic flow is sensitive to the QGP equation of state, in particular, how the shear viscosity depends on the temperature. Understanding this dependence is critical in establishing whether the lower limit of the shear viscosity over entropy ratio (η/s) reaches the lower bound of 1/4π, conjectured by the famous AdS/CFT correspondence, which attempts to relate quantum field theory and quantum gravity. The ALICE collaboration has submitted three papers for publication this year (arXiv:1602.01119, 1604.07663, 1605.02035), with unique measurements of anisotropic flow. I will review these results, and discuss how they provide vital constraints on the temperature dependence of η/s, and it's conjectured lower limit.