Bulk value of the central charge in conformally invariant critical phenomena

The concept of the central charge in a two-dimensional conformally invariant critical system is discussed. It is shown how this concept is related to a hyperuniversal amplitude ratio. In turn we illustrate the computation of its value by means of high-temperature series expansions for the cases of the Ising model and the three-state Potts model. The results are quite satisfactory and agree with the known results in these sample cases.