We study decay of a flat unstable Dp-brane in the context of boundary string field theory action. Three types of homogeneous rolling tachyons are obtained without and with Born-Infeld type electromagnetic field.

I describe some recent work in which classical solutions of Dirac-BornInfeld theory may be used to throw light on some properties of M-theory. The sources of Born-Infeld theory are the ends of strings ending on the world volume. Equivalently the fundamental string may be regarded as merely a thin and extended piece of the world volume.

M/String Theory is the currently most popular approach to a unified quantum theory of gravity and the other interactions. We still lack a complete formulation of the theory, but there is a general consensus that whatever finally emerges it will involve in some way or to some degree of approximation, p− branes, i.e. p+1-dimensional Lorentzian submanifolds Σ of a Lorentzian spacetime manifold M ....

The dynamical properties of the gauge theory of Born-Infeld type action, which is expected as the high-energy effective theory, are investigated by adding a complex scalar field to this gauge system. Especially the Coleman-Weinberg mechanism is addressed in this theory. ∗ e-mail address: [email protected] † e-mail address: [email protected] 1

D0-brane theory on a torus with a nonvanishing B field is embedded into a string theory in the weak coupling limit. It is shown that the usual supersymmetric Yang-Mills theory on a noncommutative torus can not be the whole story. The Born-Infeld action survives the noncommutative torus limit.

We argue that Einstein gravity coupled to a Born-Infeld theory provides an attractive candidate to represent dark matter and dark energy. For cosmological models, the BornInfeld field has an equation of state which interpolates between matter, p = 0 (small times), and a cosmological constant p = −ρ (large times). On galactic scales, the BornInfeld theory predicts asymptotically flat rotation cu...

We argue that Einstein gravity coupled to a Born-Infeld theory provides an attractive candidate to represent dark matter and dark energy. For cosmological models, the BornInfeld field has an equation of state which interpolates between matter, ω = 0 (small times), and a cosmological constant ω = −1 (large times). On galactic scales, the BornInfeld theory predicts asymptotically flat rotation cu...

We argue that the Dirac-Born-Infeld (DBI) action coupled to a tachyon, that is known to reproduce some aspects of open string dynamics, can be obtained from open string theory in a certain limit, which generalizes the limit leading to the usual DBI action. This helps clarify which aspects of the full open string theory are captured by this action.

We consider the Abelian Higgs model as well as the SU(2) Georgi-Glashow model in which the gauge field action is replaced by a non linear Born-Infeld action. We study soliton solutions arising in these models, namely the vortex and monopole solutions, respectively. We construct formulas which provide good approximations for the mass of the Born-Infeld deformed solitons using only the data of th...

Anisotropic cosmological spacetimes are constructed from spherically symmetric solutions to Einstein’s equations coupled to nonlinear electrodynamics and a positive cosmological constant. This is accomplished by finding solutions in which the roles of r and t are interchanged for all r > 0 (i.e. r becomes timelike and t becomes spacelike). Constant time hypersurfaces have topology R × S and in ...