(In)validity of large N orientifold equivalence
- Department of Physics, Boston University, Boston, Massachusetts 02215 (United States)
- Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)
It has been argued that the bosonic sectors of supersymmetric SU(N) Yang-Mills theory, and of QCD with a single fermion in the antisymmetric (or symmetric) tensor representation, are equivalent in the N{yields}{infinity} limit. If true, this correspondence can provide useful insight into properties of real QCD (with fundamental representation fermions), such as predictions [with O(1/N) corrections] for the nonperturbative vacuum energy, the chiral condensate, and a variety of other observables. Several papers asserting to have proven this large N 'orientifold equivalence' have appeared. By considering theories compactified on R{sup 3}xS{sup 1}, we show explicitly that this large N equivalence fails for sufficiently small radius, where our analysis is reliable, due to spontaneous symmetry breaking of charge-conjugation symmetry in QCD with an antisymmetric (or symmetric) tensor representation fermion. This theory is also chirally symmetric for small radius, unlike super-Yang-Mills theory. The situation is completely analogous to large-N equivalences based on orbifold projections: simple symmetry realization conditions are both necessary and sufficient for the validity of the large N equivalence. Whether these symmetry realization conditions are satisfied depends on the specific nonperturbative dynamics of the theory under consideration. Unbroken charge-conjugation symmetry is necessary for validity of the large N orientifold equivalence. Whether or not this condition is satisfied on R{sup 4} (or R{sup 3}xS{sup 1} for sufficiently large radius) is not currently known.
- OSTI ID:
- 20864161
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 74, Issue 10; Other Information: DOI: 10.1103/PhysRevD.74.105019; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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