In particle physics, the term hidden sector refers to the collection of yet-unobserved quantum fields and the corresponding hypothetical particles that do not directly interact via the gauge boson forces of the Standard Model. Most typically, hidden sectors include a gauge group that is independent from the Standard Model gauge group. Nevertheless, all matter including particles from the hidden sector still interacts through the force of gravity. Hidden sector may be relevant as a source of dark matter and supersymmetry breaking.
Models based on string theory usually predict hidden sectors.