AdS5 with linear dilaton and non vanishing B-field is shown to be a solution of the non critical string beta function equations. A non critical (D = 5) solution interpolating between flat space-time and AdS5, with asymptotic linear dilaton and non vanishing Bfield is also presented. This solution is free of space-time singularities and has got the string coupling constant everywhere bounded. Bo...

Kaluza-Klein monopole and H-monopole solutions, which are T-dual to each other, are the well-known solutions of string theory compactified on T . Since string theory in this case has an S-duality symmetry, we explicitly construct the corresponding dyonic solutions by expressing the D = 4 string effective action in a manifestly SL(2, R) invariant form with an SL(2, R) invariant constraint. The S...

In this paper, we propose a possible new approach towards solving the gauge hierarchy problem without supersymmetry and without extra spacetime dimensions. This approach relies on the finiteness of string theory and the conjectured stability of certain non-supersymmetric string vacua. One crucial ingredient in this approach is the idea of “misaligned supersymmetry”, which explains how string th...

We perform the dimensional reduction of the spacetime of a stack of N D3-branes by the “twist” identification of a circle to obtain a new Melvin background. In the near-horizon limit the background becomes the magnetic-flux deformed AdS5×S or AdS4×S spacetime. After analyzing the classical closed string solutions with several angular momenta in different directions of the deformed spacetimes we...

In type-II string theory compactifications on Calabi-Yau manifolds, topological string theory partition functions give a class of exact F-terms in the four dimensional effective action. We point out that in the background of constant self-dual field strength, these terms deform the central charges for D-branes wrapping Calabi-Yau manifold to include string loop corrections. We study the corresp...

We study curves of marginal stability (CMS) in five-dimensional N = 1 EN theories compactified on a circle using the D3-brane probe realization. In this realization, BPS states correspond to string webs in the affine EN 7-brane background and junction positions of the webs determine CMS. We find that there exist string webs involving infinitely many junctions. Consequently the EN theories have ...

We study curves of marginal stability (CMS) in five-dimensional N = 1 EN theories compactified on a circle using the D3-brane probe realization. In this realization, BPS states correspond to string webs in the affine EN 7-brane background and junction positions of the webs determine CMS. We find that there exist string webs involving infinitely many junctions. Consequently the EN theories have ...

The standard model for the electroweak interactions is known 1,2,3,4 to contain vortex solutions that are the usual Nielsen-Olesen U(1) vortices 5 embedded in the larger electroweak symmetry group SU(2) × U(1). After briefly describing these vortex solutions, I will discuss their stability and argue that the presence of bound states can stabilize them. Then I will draw an intimate connection be...

The classical model of an oscillator linearly coupled to a string captures, for a low price in technique, many general features of more realistic models for describing a particle interacting with a field or an atom in an electromagnetic cavity. The scattering matrix and the asymptotic in and out-waves on the string can be computed exactly and the phenomenon of resonant scattering can be introdu...

For the linear baryon string model with three massive points (three quarks) connected sequentially by the relativistic strings the initial-boundary value problem is stated and solved in general. This problem implies defining a classical motion of the system on the base of given initial position and initial velocities of string points. The given solution work reduces the initial-boundary value p...