  We construct and analyze D-branes in superstring theories in even dimensions
less than ten. The backgrounds under study are supersymmetric R^{d-1,1} \times
SL(2,R)_k / U(1) where the level of the supercoset is tuned such as to provide
bona fide string theory backgrounds. We provide exact boundary states for
D-branes that are localized at the tip of the cigar SL(2,R)/U(1) supercoset
conformal field theory. We analyze the spectra of open strings on these
D-branes and show explicitly that they are consistent with supersymmetry in
d=2,4 and 6. The low energy theory on the world-volume of the D-brane in each
case is pure Yang-Mills theory with minimal supersymmetry. In the case with
four macroscopic flat directions d=4, we realize an N=1 super Yang-Mills
theory. We interpret the backreaction for the dilaton as the running of the
gauge coupling, and study the relation between R-symmetry breaking in the gauge
theory and the backreaction on the RR axion.

High Energy Physics - Theory