THE 4TH VIRIAL-COEFFICIENT OF ANYONS

We have computed by a Monte Carlo method the fourth virial coefficient of free anyons, as a function of the statistics angle theta. It can b e fitted by a four term Fourier series, in which two coefficients are fixed by the known perturbative results at the boson and fermion point s. We compute partition functions by means of path integrals, which we represent diagrammatically in such a way that the connected diagrams give the cluster coefficients. This provides a general proof that all cluster and virial coefficients are finite. We give explicit polynomia l approximations for all path integral contributions to all cluster co efficients, implying that only the second virial coefficient is statis tics dependent, as is the case for two-dimensional exclusion statistic s. The assumption leading to these approximations is that the tree dia grams dominate and factorize.