Whatever it is otherwise, string theory turns out to be an organizational principle that subsumes a wealth of effective quantum field theories together with hints for their UV-completion. As such, string theory reveals a multitude of equivalences between superficially very different-looking (classes of) quantum field theories, or between various limits (notably strong/weak coupling limits) of various different-looking quantum field theories. Large classes of these equivalences go by the name of “dualities”:
There is also
the relation between 11-dimensional supergravity and the various string theories, see
under construction
| reduction from 11d | electric σ-model | weak/strong coupling duality | magnetic σ-model |
|---|---|---|---|
| M2-brane in 11d sugra EFT | electric-magnetic duality | M5-brane in 11d sugra EFT | |
| HW reduction | |||
| on orientifold K3 | on orientifold K3 | ||
| F1-brane in heterotic supergravity | S-duality | black string in heterotic sugra | |
| HW reduction | |||
| on orientifold T4 | on orientifold T4 | ||
| F1-brane in heterotic supergravity | S-duality | black string in type IIA sugra | |
| KK reduction | |||
| on K3 | on K3 | ||
| F1-brane in IIA sugra | S-duality | black string in heterotic sugra | |
| KK reduction | |||
| on | on | ||
| F1-brane in IIA sugra | S-duality | black string in type IIA sugra | |
| F-reduction | T-duality on | ||
| F1-brane in IIB sugra | S-duality | D1-brane in 10d IIB sugra | |
| U-duality | T-duality on | ||
| D3-brane in IIB sugra | S-duality | D3-brane in IIB sugra |
The original article suggesting the relation of 11d sugra to string theory is
An original article collecting all the weak/strong electric/magnetic dualities is
A detailed discussion of dualities induced on K3-compactifications is in