Description
Working in a sector of fixed and large global charge leads to important simplifications in the study of strongly-coupled CFTs. It is possible to calculate the conformal data as an expansion in inverse powers of the large charge which acts as a control parameter. Fixing the charge leads to spontaneous symmetry breaking both in the global and space-time symmetries. The fixed-charge theory as a result exhibits non-relativistic traits in the spectrum of Goldstone excitations.
It is also possible to use the large-charge approach directly on non-relativistic systems, so called non-relativistic CFTs which are invariant under the Schrödinger group. An interesting example of this class is the unitary Fermi gas which can be realized in the laboratory.
