Matrix membrane big bangs andD-brane production

Abstract

We construct Matrix Membrane theory in pp wave backgrounds that have a null linear dilaton in Type IIB string theory. Such backgrounds can serve as toy models of big bang cosmologies. At late times only abelian degrees of freedom survive, and if the Kaluza-Klein modes along one of the directions of the membrane decouple, standard perturbative strings emerge. Near the "big bang", non-abelian configurations of fuzzy ellipsoids are present, as in the Type IIA theories. A generic configuration of these shrink to zero volume at late times. However, the Kaluza Klein modes (which can be thought of as states of (p, q) strings in the original IIB theory) can be generically produced in pairs in both pp wave and flat backgrounds in the presence of time dependence. Indeed, if we require that at late times the theory evolves to the perturbative string vacuum, these modes must be prepared in a squeezed state with a thermal distribution at early times.

Supersymmetric intersecting branes in time-dependent backgrounds

“…where we have used the gauge condition to set g uv = −1, i.e., 17) and f α (u) and g(u) are given by 18) respectively. If we compactify y α , we may find a time-dependent cosmological solution.…”

Holography and Cosmological Singularities

“…The size of the ellipsoids is now time dependent : with some initial size the equations of motion may be used to examine the size at later times. Numerical results [2] show that with generic initial conditions, the size oscillates with an amplitude decaying fast with time. In other words, at late times we are left with only the abelian configurations which can be now interpreted as fundamental strings.…”

“…The Type IIB version of this background shows a richer structure [2]. The background is once again given by (1) and (2) where both x − and x 8 are compact,…”

“…It would be worthwhile to find similar situations with an additional length scale with the hope that tuning the dimensionless ratio would allow us to go to a regime where some class of nonableian configurations become important. One such example is provided by pp-waves [2], [1]. The string frame metric (1) is now modified to…”

“…This talk is based on work done in collaboration with Jeremy Michelson, K. Narayan and Sandip Trivedi [1,2,3,4].…”