  In 6D general relativity with a scalar field as a source of gravity, a new
type of static wormhole solutions is presented: such wormholes connect our
universe with a small 2D extra subspace with a universe where this extra
subspace is large, and the whole space-time is effectively 6-dimensional. We
consider manifolds with the structure M0 x M1 x M2 , where M0 is 2D Lorentzian
space-time while each of M1 an M2 can be a 2-sphere or a 2-torus. After
selecting possible asymptotic behaviors of the metric functions compatible with
the field equations, we give two explicit examples of wormhole solutions with
spherical symmetry in our space-time and toroidal extra dimensions. In one
example, with a massless scalar field (it is a special case of a well-known
more general solution), the extra dimensions have a large constant size at the
"far end"; the other example contains a nonzero potential $V(\phi)$ which
provides a 6D anti-de Sitter asymptotic, where all spatial dimensions are
infinite.
