D H Bailey et al 2006 J. Phys. A: Math. Gen. 39 12271 doi:10.1088/0305-4470/39/40/001
D H Bailey1, J M Borwein2 and R E Crandall3
Show affiliationsFrom an experimental-mathematical perspective we analyse 'Ising-class' integrals. These are structurally related n-dimensional integrals we call Cn, Dn, En, where Dn is a magnetic susceptibility integral central to the Ising theory of solid-state physics. We first analyse 
We had conjectured—on the basis of extreme-precision numerical quadrature—that Cn has a finite large-n limit, namely C∞ = 2 e−2γ, with γ being the Euler constant. On such a numerological clue we are able to prove the conjecture. We then show that integrals Dn and En both decay exponentially with n, in a certain rigorous sense. While Cn, Dn remain unresolved for n ≥ 5, we were able to conjecture a closed form for E5. Our experimental results involved extreme-precision, multidimensional quadrature on intricate integrands; thus, a highly parallel computation was required.
05.50.+q Lattice theory and statistics (Ising, Potts, etc.)
33F10 Symbolic computation (Gosper and Zeilberger algorithms, etc.) (See also 68W30)
82B20 Lattice systems (Ising, dimer, Potts, etc.) and systems on graphs
Issue 40 (6 October 2006)
Received 2 June 2006, in final form 14 August 2006
Published 19 September 2006
D H Bailey et al 2006 J. Phys. A: Math. Gen. 39 12271
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