Tachyon condensation in cubic superstring field theory

It has been conjectured that at the stationary point of the tachyon potential for the non-BPS D-brane or brane-anti-D-brane pair, the negative energy density cancels the brane tension. We study this conjecture using a cubic superstring field theory with insertion of a double-step inverse picture changing operator. We compute the tachyon potential at levels (1/2, 1) and (2, 6). In the first case we obtain that the value of the potential at the minimum is 97.5% of the non-BPS D-brane tension. Using a special gauge in the second case we get 105.8% of the tension. (C) 2002 Elsevier Science B.V. All rights reserved.