String Perturbation Theory on the Schwinger-Keldysh Time Contour

Area of Science:

• Theoretical Physics
• Quantum Field Theory
• String Theory

Background:

• Non-equilibrium quantum systems with matrix degrees of freedom are challenging to analyze.
• The Schwinger-Keldysh formulation provides a framework for studying such systems out of equilibrium.
• Topological expansions are crucial for understanding the properties of quantum field theories and their duals.

Purpose of the Study:

• To perform a large-N expansion within the Schwinger-Keldysh formulation for matrix-valued nonequilibrium quantum systems.
• To investigate universal features of the anticipated dual string theory.
• To explore a refined topological genus expansion associated with the Schwinger-Keldysh time contour.

Main Methods:

• Application of the large-N expansion technique.
• Utilizing the Schwinger-Keldysh formulation for nonequilibrium quantum systems.
• Performing a Keldysh rotation to analyze world sheet structures.

Main Results:

• A significant refinement of the topological genus expansion was discovered.
• The future time instant in the Schwinger-Keldysh contour is associated with a distinct world sheet genus expansion.
• Post-Keldysh rotation, world sheets naturally decompose into classical and quantum parts.

Conclusions:

• The study provides new insights into the structure of dual string theories for nonequilibrium quantum systems.
• The refined genus expansion offers a more detailed understanding of the Schwinger-Keldysh formalism.
• The decomposition of world sheets highlights fundamental aspects of quantum dynamics in these systems.