  I discuss the von Neumann entanglement entropy in two-dimensional quantum
Lifshitz criical point, namely in Rokhsar-Kivelson type critical wavefunctions.
I follow the approach proposed by B. Hsu et al. [Phys. Rev. B 79, 115421
(2009)], but point out a subtle problem concerning compactification of replica
boson fields: although one can define a set of new boson fields by linear
combinations of the original fields, the new fields are not compactified
independently. In order to systematically study boundary conformal field theory
of multicomponent free bosons, I employ a geometric formulation based on
compactification lattices. The result from the boundary conformal field theory
agrees exactly with alternative calculations by J.-M. Stephan et al. [Phys.
Rev. B 80, 184421 (2009)], confirming its universality as argued originally by
B. Hsu et al.
