  SLE curves describe the scaling limit of interfaces from many 2D lattice
models. Heuristically speaking, the SLE partition function is the continuum
counterpart of the partition function of the corresponding discrete model. It
is well known that conformally welding of Liouville quantum gravity (LQG)
surfaces gives SLE curves as the interfaces. In this paper, we demonstrate in
several settings how the SLE partition function arises from conformal welding
of LQG surfaces. The common theme is that we conformally weld a collection of
canonical LQG surfaces which produces a topological configuration with more
than one conformal structure. Conditioning on the conformal moduli, the surface
after welding is described by Liouville conformal field theory (LCFT), and the
density of the random moduli contains the SLE partition function for the
interfaces as a multiplicative factor. The settings we treat includes the
multiple SLE for $\kappa\in (0,4)$, the flow lines of imaginary geometry on the
disk with boundary marked points, and the boundary Green function. These
results demonstrate an alternative approach to construct and study the SLE
partition function, which complements the traditional method based on
stochastic calculus and differential equation.
