One-Loop Riemann Surfaces in Schnabl Gauge

Understand

Due to a peculiar behavior at the open string midpoint, loop diagrams in Schnabl gauge were expected to fail to produce the relevant closed string moduli.

• We find that closed string moduli are generated because the Riemann surfaces are built with slanted wedges: semi-infinite strips whose edges have parameterizations related by scaling.
• We examine in detail one-loop string diagrams and find that the closed string modulus is always produced.
• Moreover, the conformal maps simplify so greatly that both closed and open moduli become simple calculable functions of the Schwinger parameters, a simplification that occurs neither in Siegel gauge nor in light-cone gauge.