A new critical exponent 'coppa' and its logarithmic counterpart 'hat coppa'

It is well known that standard hyperscaling breaks down above the upper critical dimension d c , where the critical exponents take on their Landau values. Here, we show that this is because in standard formulations in the thermodynamic limit, distance is measured on the correlation-length scale. However, the correlationlength scale and the underlying length scale of the system are not the same at or above the upper critical dimension. Above d c they are related algebraically through a new critical exponent , while at d c they differ through logarithmic corrections governed by an exponent . Taking proper account of these different length scales allows one to extend hyperscaling to all dimensions.