STABLE NON-BPS STATES IN STRING THEORY

Many string theories contain states which are not BPS, but are stable due to charge conservation. In many cases the description of these sta tes in the strong coupling limit remains unknown despite the existence of a weakly coupled dual theory. However, we show that in some cases duality symmetries in string theory do enable us to identify these sta tes in the strong coupling limit and calculate their masses. We also s peculate that in some of the other cases the missing states might aris e from non-supersymmetric analog of D0-branes.