  The low-energy physics of three-leg frustrated antiferromagnetic spin-S tubes
in the vicinity of the upper critical field are studied. Utilizing the
effective field theory based on the spin-wave approximation, we argue that in
the intermediate-interchain-coupling regime, the ground state exhibits a vector
chiral order or an inhomogeneous magnetization for the interchain (rung)
direction and the low-energy excitations are described by a one-component
Tomonaga-Luttinger liquid (TLL). In both chiral and inhomogeneous phases, the
Z_2 parity symmetry along the rung direction is spontaneously broken. It is
also predicted that a two-component TLL appears and all the symmetries are
restored in the strong-rung-coupling case.
