We review and extend our recent work on the planar (large N) equivalence between gauge theories with varying degrees of supersymmetry. The main emphasis is on the planar equivalence between N = 1 gluodynamics (super-Yang-Mills theory) and a nonsupersymmetric "orientifold field theory". We outline an "orientifold" large N expansion, analyze its possible phenomenological consequences in one-flavor massless QCD, and make a first attempt at extending the correspondence to three massless flavors. An analytic calculation of the quark condensate in one-flavor QCD starting from the gluino condensate in Af= 1 gluodynamics is thoroughly discussed. We also comment on a planar equivalence involving A" = 1 supersymmetry, on "chiral rings" in non-supersymmetric theories, and on the origin of planar equivalence from an underlying, non-tachyonic type-0 string theory. Finally, possible further directions of investigation, such as the gauge/gravity correspondence in large-AT orientifold field theory, are briefly discussed.
|Original language||English (US)|
|Title of host publication||From Fields to Strings|
|Subtitle of host publication||Circumnavigating Theoretical Physics: Ian Kogan Memorial Collection|
|Publisher||World Scientific Publishing Co.|
|Number of pages||92|
|State||Published - Jan 1 2005|