Spectral branes

We study the objects (called spectral branes or S-branes) which are obtaine d by imposing non-local spectral boundary conditions at the boundary of the world sheet of the bosonic string. They possess many nice properties which make them an ideal test ground for the string theory methods. Depending on a particular choice of the boundary operator S-branes may be commutative o r non-commutative. We demonstrate that projection of the B-field on the bra ne directions (i.e. on the components which actually influence the boundary conditions) is done with the help of the chirality operator. We show that the T-duality transformation maps an S-brane to another S-brane. At the exp ense of introducing non-local interactions in the bulk we construct also a duality transformation between S-branes and D-branes or open strings.