Undoing orbifold quivers

A number of new papers have greatly elucidated the derivation of quiver gaugetheories from D-branes at a singularity. A complete story has now beendeveloped for the total space of the canonical line bundle over a smooth Fano2-fold. In the context of the AdS/CFT conjecture, this corresponds to eight ofthe ten regular Sasaki-Einstein 5-folds. Interestingly, the two remainingspaces are among the earliest examples, the sphere and T^{11}. I show how toobtain the (well-known) quivers for these theories by interpreting thecanonical line bundle as the resolution of an orbifold using the McKaycorrespondence. I then obtain the correct quivers by undoing the orbifold. Ialso conjecture, in general, an autoequivalence that implements the orbifoldgroup action on the derived cateory. This yields a new order twoautoequivalence for the Z_2 quotient of the conifold.Comment: 18 pages, LaTeX, uses utarticle.cls, xypic, v2:minor corrections, v3:more minor correction