A Note on Tachyons in the $D3+{\bar {D3}}$ System
  The periodic bounce of Born-Infeld theory of $D3$-branes is derived, and the BPS limit of infinite period is discussed as an example of tachyon condensation. The explicit bounce solution to the Born--Infeld action is interpreted as an unstable fundamental string stretched between the brane and its antibrane. 
Yan-Gang Miao, Harald J.W. M\"uller-Kirsten, Dae Kil Park