Proof of vanishing cohomology at the tachyon vacuum
arXiv:hep-th/0606142 · doi:10.1088/1126-6708/2007/02/096
Abstract
We prove Sen's third conjecture that there are no on-shell perturbative excitations of the tachyon vacuum in open bosonic string field theory. The proof relies on the existence of a special state A, which, when acted on by the BRST operator at the tachyon vacuum, gives the identity. While this state was found numerically in Feynman-Siegel gauge, here we give a simple analytic expression.
19 pages, 4 figures; v2: references added