Space-times of boosted p-branes, and CFT in infinite-momentum frame

We study the space-times of the near-horizon regions in D3-brane, M2-brane and M5-brane configurations, in cases where there is a pp-wave propagating along a direction in the world-volume. While non-extremal configurations of this kind locally have the same Carter-Novotny-Horsky-type metrics as those without the wave, taking the BPS limit results instead in Kaigorodov-type metrics, which are homogeneous, but preserve 1/4 of the supersymmetry, and have global and local structures that are quite different from the corresponding anti-de Sitter space-times associated with solutions where there is no pp-wave. We show that the momentum density of the system is non-vanishing and held fixed under the gravity decoupling limit. In view of the AdS/CFT correspondence, M-theory and type IIB theory in the near-horizon region of these boosted BPS-configurations specifies the corresponding CFT on the boundary in an infinitely boosted frame with constant momentum density. We model the microstates of such boosted configurations (which account for the microscopic counting of near-extremal black holes in D = 7, D = 9 and D = 6) by those of a boosted dilute massless gas in a d = 4, d = 3 and d = 6 space-time respectively. Thus we obtain a simple description far the entropy of 2-charge black holes in D = 7, 9 and 6 dimensions. The paper includes constructions of generalisations of the Kaigorodov and Carter-Novotny-Horsky metrics in arbitrary space-time dimensions, and an investigation of their properties. (C) 1999 Elsevier Science B.V.