Holonomy of the Ising model form-factors

Sep, 2006
39 pages
Published in:
  • J.Phys.A 40 (2007) 75-112
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Abstract:
We study the Ising model two-point diagonal correlation function C(N,N) C(N,N) by presenting an exponential and form factor expansion in an integral representation which differs from the known expansion of Wu, McCoy, Tracy and Barouch. We extend this expansion, weighting, by powers of a variable λ\lambda, the jj-particle contributions, fN,N(j) f^{(j)}_{N,N}. The corresponding λ \lambda extension of the two-point diagonal correlation function, C(N,N:λ) C(N,N: \lambda), is shown, for arbitrary λ\lambda, to be a solution of the sigma form of the Painlev{\'e} VI equation introduced by Jimbo and Miwa. Linear differential equations for the form factors fN,N(j) f^{(j)}_{N,N} are obtained and shown to have both a ``Russian doll'' nesting, and a decomposition of the differential operators as a direct sum of operators equivalent to symmetric powers of the differential operator of the elliptic integral E E. Each fN,N(j) f^{(j)}_{N,N} is expressed polynomially in terms of the elliptic integrals E E and K K. The scaling limit of these differential operators breaks the direct sum structure but not the ``Russian doll'' structure. The previous λ \lambda-extensions, C(N,N:λ) C(N,N: \lambda) are, for singled-out values λ=cos(πm/n) \lambda= \cos(\pi m/n) (m,nm, n integers), also solutions of linear differential equations. These solutions of Painlev\'e VI are actually algebraic functions, being associated with modular curves.
Note:
  • 39 pages Subj-class: Mathematical Physics: Statistical Mechanics: Computational Physics MSC-class: 33E17, 33E05, 33Cxx, 33Dxx, 14Exx, 14Hxx, 34M55, 47E05, 34Lxx, 34Mxx, 14Kxx
  • 05.50.+q
  • 02.30.Gp
  • 05.10.-a
  • 02.30.Hq
  • 02.40.Re
  • 02.30.-f
  • 04.20.Jb