  We investigate the nature of quantum spin liquid (QSL) phase of the
spin-$1/2$ nearest-neighbor XXZ antiferromagnet on the kagome lattice. Recent
numerical calculations suggest that such a kagome spin liquid is insensitive to
the XXZ anisotropy and is adjacent to a chiral spin liquid phase. Reformulating
the problem in terms of a $U(1)$ lattice gauge theory with dynamical bosonic
spinons, we propose that the kagome spin liquid can be understood as a
deconfined critical phase extended by the $U(1)$ gauge fluctuation from a
deconfined critical point between a symmetry-protected topological phase and a
superfluid phase. Crucially, the stability of this QSL is ensured by the gauge
fluctuation and hence our description necessarily falls beyond the conventional
mean-field constructions of QSLs. Our work also makes an interesting connection
between the critical spin liquid, deconfined criticality, symmetry protected
topological phase and topological order.
