The high-temperature susceptibility of the q-state Potts model behaves as Γ|T − Tc| as T → Tc+, while for T → Tc− one may define both longitudinal and transverse susceptibilities, with the same power law but different amplitudes ΓL and ΓT . We extend a previous analytic calculation of the universal ratio Γ/ΓL in two dimensions to the low-temperature ratio ΓT /ΓL, and test both predictions with ...

The scaling form of the free energy near a critical point allows for the definition of various thermodynamical amplitudes and the determination of their dependence on the microscopic nonuniversal scales. Universal quantities can be obtained by considering special combinations of the amplitudes. Together with the critical exponents they characterize the universality classes and may be useful qua...

1 Laboratoire de Physique des Matériaux, Université Henri Poincaré, Nancy I, BP 239, F-54506 Vandœuvre les Nancy Cedex, France [email protected] 2 Istituto Nazionale di Fisica Nucleare, Universitá Milano-Bicocca, Piazza delle Scienze 3, 20126, Milano, Italia [email protected] 3 Landau Institute for Theoretical Physics, Russian Academy of Sciences, Chernogolovka 142432, Russia lev@lan...

Using results from conformal field theory, we compute several universal amplitude ratios for the two-dimensional Ising model at criticality on a symmetric torus. These include the correlation-length ratio x⋆ = limL→∞ ξ(L)/L and the first four magnetization moment ratios V2n = 〈M2n〉/〈M2〉n. As a corollary we get the renormalized four-point coupling constant for the massless theory on a symmetric ...

We present analytical and numerical results for the specific heat and susceptibility amplitude ratios in parallel plate geometries. The results are derived using field-theoretic techniques suitable to describe the system in the bulk limit, i.e., (L/j6)@1, where L is the distance between the plates and j6 is the correlation length above ~1! and below (2) the bulk critical temperature. Advantages...

We consider strips of Ising spins at criticality. For strips of width N sites, subdominant (additive) finite-size corrections to scaling are assumed to be of the form a(k)/N(k) for the free energy, and b(k)/N(k) for inverse correlation length, with integer values of k. We investigate the set {a(k),b(k)} (k≥2) by exact evaluation and numerical transfer-matrix diagonalization techniques, and thei...

Universal functions and amplitude ratios associated with the classes of second order phase transitions are used as additional tests of the prediction that the pure glue, SU(2), nite-temperature, deconnning phase transition is in the universality class of the three-dimensional Ising model. Published gauge theory Monte Carlo data, give values that can be compared with theory and Ising model numer...