Exact partition function of SU (m|n) supersymmetric Haldane-Shastry spin chain

By taking the freezing limit of a spin Calogero-Sutherland model containing 'anyon like' representation of the permutation algebra, we derive the exact partition function of SU(m vertical bar n) supersymmetric Haldane-Shastry (HS) spin chain. This partition function allows us to study global properties of the spectrum like level density distribution and nearest neighbour spacing distribution. It is found that, for supersymmetric HS spin chains with large number of lattice sites, continuous part of the energy level density obeys Gaussian distribution with a high degree of accuracy. The mean value and standard deviation of such Gaussian distribution can be calculated exactly. We also conjecture that the partition function of supersymmetric HS spin chain satisfies a duality relation under the exchange of bosonic and fermionic spin degrees of freedom. (c) 2006 Elsevier B.V. All rights reserved.