Four Loop Order Beta Function of Nonlinear σ\sigma Models in Symmetric Spaces

1989
16 pages
Published in:
  • Nucl.Phys.B 316 (1989) 663-678
  • Published: 1989

Citations per year

1990199920082017202502468
Abstract: (Elsevier)
The beta-function for the grassmannian nonlinear σ-model of symmetry U (N) U (p) ∗ U (N−p) has been calculated directly in four-loop order in d =2+ ε dimensions. Using isomorphisms and information from 1 N expansions I obtain the four-loop β-function for a large class of manifolds. Consequences are: (i) the degeneracy of the exponent ν for chiral models on the group manifolds SU( N ) and SO( N ) in three-loop order is lifted in four-loop order; (ii) the conductivity exponent at the mobility edge for the orthogonal case acquires a negative correction; (iii) the β-function bends over in the symplectic (i.e. spin-orbit coupling) case which suggests a nontrivial mobility edge fixed-point in d = 2 dimensions.
  • FIELD THEORETICAL MODEL: SIGMA
  • NONLINEAR
  • MODEL: GRASSMANN
  • RENORMALIZATION: BETA FUNCTION
  • EXPANSION 1/N
  • SYMMETRY: SU(N)
  • SYMMETRY: SO(N)
  • PERTURBATION THEORY: HIGHER-ORDER
  • FIELD THEORY: CRITICAL PHENOMENA
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