The Low Energy Dynamics of Non-BPS Branes

In this talk we will discuss the low energy dynamics of non-BPS branes constructed as stable brane/anti-brane pairs at an orbifold. In particular we will determine the effective field theory and compare its predictions with those of the full open string theory. While the position and vector degrees of freedom have the familiar form found in supersymmetric gauge theories, the massless modes orginating in the tachyonic sector display novel non-commuting flat directions. We will show that these flat directions persist to al orders in alpha’. Finally we will briefly report on the open string loop corrections.