Spectral branes

We study the objects (called spectral branes or S-branes) which are obtainedby imposing non-local spectral boundary conditions at the boundary of the worldsheet of the bosonic string. They possess many nice properties which make theman ideal test ground for the string theory methods. Depending on a particularchoice of the boundary operator S-branes may be commutative or non-commutative.We demonstrate that projection of the B-field on the brane directions (i.e. onthe components which actually influence the boundary conditions) is done withthe help of the chirality operator. We show that the T-duality transformationmaps an S-brane to another S-brane. At the expense of introducing non-localinteractions in the bulk we construct also a duality transformation betweenS-branes and D-branes or open strings.Comment: 14 page