Prof Andre Lukas

Abstract:

We present a new scenario for baryogenesis in the context of heterotic brane-world models. The baryon asymmetry of the universe is generated at a small-instanton phase transition which is initiated by a moving brane colliding with the observable boundary. We demonstrate, in the context of a simple model, that reasonable values for the baryon asymmetry can be obtained. As a byproduct we find a new class of moving-brane cosmological solutions in the presence of a perfect fluid. © 2002 The American Physical Society.

Abstract:

The effective action for five-dimensional heterotic M theory in the presence of five-branes is systematically derived from Hořava-Witten theory coupled to an M5-brane world-volume theory. This leads to a five-dimensional N=1 gauged supergravity theory on S1/Z2 coupled to four-dimensional N=1 theories residing on the two orbifold fixed planes and an additional bulk three-brane. We analyze the properties of this action, particularly the four-dimensional effective theory associated with the domain-wall vacuum state. The moduli Kähler potential and the gauge-kinetic functions are determined along with the explicit relations between four-dimensional superfields and five-dimensional component fields. ©2002 The American Physical Society.

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.