Theoretical Physics(DTP)
Physique théorique (DPT)

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Margaret E. CARRINGTON
Brandon University

Transport Theory Beyond Binary Collisions

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Transport theory provides a practical method to study many-body nonequilibrium systems, both relativistically and nonrelativistically.

The contribution of two-loop self-energy diagrams to the collision term in the transport equation can be understood physically in terms of binary collisions. Consequently, it's sufficient to work at 2-loop order only if it's true that dissipation processes are dominated by binary collisions.

When dealing with a relativistic system at high energy and density, multi-particle interactions and production processes will be present, and thus the binary collision aproximation will not be adequate. The quark-gluon plasma is a prominent example of such a system. We calculate contributions to the collision term from self-energy diagrams at three loops, and show that these contributions correspond to multi-particle collisions and production processes.