Probing universality in the gravity duals of N = 1 SYM by γ deformations

Recently, a one-parameter deformation of the Maldacena-Nunez background was constructed in hep-th/0505100. According to the Lunin-Maldacena conjecture, the background is dual to pure N = 1 SYM in the IR coupled to a KK sector whose dynamics is altered by a dipole deformation that is proportional to the deformation parameter γ. Thus, the deformation serves to identify the aspects of the gravity backgrounds that bear the effects of the KK sector, hence non-universal in the dual gauge theory. We make this idea concrete by studying a Penrose limit of the deformed MN background. We obtain an exactly solvable pp-wave that is conjectured to describe the IR dynamics of KK-hadrons in the field theory. The spectrum, the thermal partition function and the Hagedorn temperature are calculated. Interestingly, the Hagedorn temperature turns out to be independent of the deformation parameter