Exact Two-Dimensional Superconformal R Symmetry and c Extremization

We uncover a general principle dubbed c extremization, which determines the exact R symmetry of a two-dimensional unitary superconformal field theory with N = (0, 2) supersymmetry. To illustrate its utility, we study superconformal theories obtained by twisted compactifications of four-dimensional N = 4 super-Yang-Mills theory on Riemann surfaces and construct their gravity duals. DOI: 10.1103/PhysRevLett.110.061601