Physics

Quark Plasma Reexamined

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Science  14 Jul 2006:
Vol. 313, Issue 5784, pp. 149
DOI: 10.1126/science.313.5784.149a

A fraction of a second after the Big Bang, the universe is thought to have consisted of a hot primordial soup of fundamental particles: a quark-gluon plasma. Researchers have sought to recreate this early matter by smashing heavy ions together. Because the quark soup lasts only for a short time and quarks cannot exist in free form, the formation of the plasma is diagnosed by what other kinds of particles emerge from the collision. Analysis of this collision process is predicated on important assumptions about the fluid dynamic properties of the quark plasma and the strength of interactions among the particles. One view has been that the data support the existence of a strongly coupled quark-gluon plasma.

Asakawa et al. propose an alternative picture to explain the fluid dynamics. Their analysis reaches back to theories from the 1960s that were developed to understand particle transport in turbulent magnetically confined plasmas. In this environment, excited oscillations of the plasma can scatter particles and strongly reduce the plasma viscosity, a phenomenon that came to be called anomalous transport. The authors find that a similar process, with quark-gluon forces replacing electromagnetic waves, could give rise to an anomalous viscosity in a weakly coupled plasma and thereby explain the fluid dynamic behavior revealed in recent experimental heavy-ion collision data. — DV

Phys. Rev. Lett. 96, 252301 (2006).

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