  We construct analytic solutions of open bosonic string field theory for any
exactly marginal deformation in any boundary conformal field theory when
properly renormalized operator products of the marginal operator are given. We
explicitly provide such renormalized operator products for a class of marginal
deformations which include the deformations of flat D-branes in flat
backgrounds by constant massless modes of the gauge field and of the scalar
fields on the D-branes, the cosine potential for a space-like coordinate, and
the hyperbolic cosine potential for the time-like coordinate. In our
construction we use integrated vertex operators, which are closely related to
finite deformations in boundary conformal field theory, while previous analytic
solutions were based on unintegrated vertex operators. We also introduce a
modified star product to formulate string field theory around the deformed
background.
