Editing Modular invariance (section)

{{Unreferenced stub|auto=yes|date=December 2009}}
In [[theoretical physics]], '''modular invariance''' is the invariance under the [[group (mathematics)|group]] such as SL(2,Z) of [[large diffeomorphism]]s of the [[torus]]. The name comes from the classical name [[modular group]] of this group, as in [[modular form]] theory.

In [[string theory]], modular invariance is an additional requirement for [[one-loop diagram]]s. This helps in getting rid of some [[global anomaly|global anomalies]] such as the [[gravitational anomaly|gravitational anomalies]]. 

Equivalently, in [[two-dimensional conformal field theory]] the torus partition function must be invariant under the modular group [[SL(2,Z)]].