  We analyze deformations of two-dimensional conformal field theory (CFT) from
the perspective of classical bosonic closed string field theory (SFT). The
latter can be viewed as a version of Wilsonian renormalization group (RG)
improved conformal perturbation theory, where the renormalization scheme is
defined through the choice of string vertices in the construction of SFT.
Furthermore, the CFT data at the RG fixed point can be recovered from the
spectrum and amplitudes of string field fluctuations. As applications, we
construct the Horowitz-Polchinski "string star" solution in SFT, and a solution
of tachyon-dilaton condensation that deforms the noncompact boson to minimal
models by creating a pair of "Runkel-Watts walls".
