Monopoles and dyons in non-commutative geometry

Taking advantage of the equivalence between supersymmetric Yang-Mills theoryon non-commutative spaces and the field theory limit of D3-branes in thebackground of NSNS 2-form field, we investigate the static properties ofmagnetic monopoles and dyons using brane construction techniques. When parallelD3-branes are separated by turning on a Higgs vacuum expectation value,D-strings will stretch between them at an angle which depends on the value ofthe background 2-form potential. These states preserve half of thesupersymmetries and have the same masses as their commutative counterparts inthe field theory limit. We also find stable (p,q)-dyons and string junctions.We find that they do not preserve any supersymmetry but have the same masses astheir commutative counterparts. In the field theory limit, the (p,q)-dyons andthe string junctions restore 1/2 and 1/4 of the 16 supersymmetries,respectively.Comment: 16 pages, LaTeX, 3 eps figures; v2. Counting of the number of preserved supercharges of (p,q) dyons before taking the field theory limit modified. Conclusions unchanged in the field theory limit. References added; v3. minor change