The pp-wave limits of orbifolded AdS5 x S5

Using the supergravity solution of N-1 D3-branes probing A(N2-1) singularities we study the pp-wave limit of AdS(5) x S-5/Z(N2). We show that there are two different pp-wave limits. One is the orbifold of the pp-wave limit of AdS5 x S-5. In this case there is no symmetry enhancement. The other case is the same as the pp-wave limit of AdS(5) x S-5 and therefore we again see the maximal supersymmetry. We will also identify operators in the four-dimensional N = 2 SU(N-1)(N2) gauge theory which correspond to stringy excitations in the orbifolded pp-wave geometry. The existence of the maximal pp-wave geometry indicates that there is a subsector of the corresponding N = 2 gauge theories which has enhanced N = 4 supersymmetry. We also study the pp-wave limits of AdS(7,4) x S-4.7/Z(N). (C) 2002 Published by Elsevier Science B.V.