Conformal anomalies of CFT's with boundaries

The trace anomaly of conformal field theories in four dimensions is characterized by 'a' and 'c'-functions. The scaling properties of the effective action of a CFT in the presence of boundaries is shown to be determined by a, c and two new functions (charges) related to boundary effects. The boundary charges are computed for different theories and different boundary conditions. One of the boundary charges depends on the bulk c charge.