Nonanalyticity of the Callan-Symanzik Beta function of two-dimensional O(N) models

May, 2000
17 pages
Published in:
  • J.Phys.A 33 (2000) 8155-8170
e-Print:
Report number:
  • DFTT-21-2000,
  • IFUP-TH-2000-16

Citations per year

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Abstract:
We discuss the analytic properties of the Callan-Symanzik beta-function beta(g) associated with the zero-momentum four-point coupling g in the two-dimensional phi^4 model with O(N) symmetry. Using renormalization-group arguments, we derive the asymptotic behavior of beta(g) at the fixed point g^*. We argue that beta'(g) = beta'(g^*) + O(|g-g^*|^{1/7}) for N=1 and beta'(g) = beta'(g^*) + O(1/\log |g-g^*|) for N > 2. Our claim is supported by an explicit calculation in the Ising lattice model and by a 1/N calculation for the two-dimensional phi^4 theory. We discuss how these nonanalytic corrections may give rise to a slow convergence of the perturbative expansion in powers of g.
Note:
  • 18 pages. Discussion on Logarithmic CFT added in Appendix A. References updated. A note on the interpretation of the p_5 constant added. Final version, accepted for publication in Journal of Physics A Report-no: DFTT 21/2000, IFUP-TH/2000-16
  • phi**n model: 4
  • dimension: 2
  • symmetry: O(N)
  • renormalization group: beta function
  • analytic properties
  • asymptotic behavior
  • Ising model
  • critical phenomena
  • Borel transformation
  • field theory: conformal