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Abstract:

Under certain conditions some solutions to five-dimensional heterotic M theory can be accurately described by the four-dimensional action of the theory. We consider the connection between solutions of four- and five-dimensional heterotic M theory when moving five-branes are present in the bulk. We begin by describing how to raise the known four-dimensional moving brane solutions to obtain approximate solutions to the five-dimensional theory, presenting for the first time the metric template necessary for this procedure. We then present the first solutions to the five-dimensional theory containing moving five-branes. We then discuss the correspondence between solutions of the five- and four-dimensional actions as presented. Specifically, we show that our exact, five-dimensional solution only corresponds to one of the previously known four-dimensional solutions when the embedded five-brane is static. In other words, higher Kaluza-Klein modes are essential in the description of the five-brane’s motion in our new solution. © 2002 The American Physical Society.

Abstract:

We construct cosmological solutions of four-dimensional effective heterotic M theory with a moving five-brane and evolving dilaton and T modulus. It is shown that the five-brane generates a transition between two asymptotic rolling-radii solutions. Moreover, the five-brane motion always drives the solutions towards strong coupling asymptotically. We present an explicit example of a negative-time branch solution which ends in a brane collision accompanied by a small-instanton transition. The five-dimensional origin of some of our solutions is also discussed.

Abstract:

A plausible explanation for the existence of additional light sterile neutrinos is that they correspond to modulini, fermionic partners of moduli, which propagate in new large dimensions. We discuss the phenomenological implications of such states and show that solar neutrino oscillation is well described by small angle MSW oscillation to the tower of Kaluza Klein states associated with the modulini. We also consider how all oscillation phenomena can be explained in a model including bulk neutrino states.