  Spectrum of excitons in double-quantum-well structures is calculated in
tilted magnetic field. It is shown that spectrum becomes asymmetric in
quasimomentum if a transverse in respect to growth direction component of
magnetic field is nonzero. A transition from $k$-space direct exciton ground
state to $k$-space indirect one accompanied by sharp quenching of
photoluminescense is described.
