We discuss the problem of competition between a superconducting (SC) ordered state and a charge-density wave (CDW) state in stripe phases of high T_c superconductors. We consider an effective model for each stripe motivated by studies of spin-gapped electronic ladder systems. We analyze the problem of dimensional crossover arising from interstripe SC and CDW couplings using non-Abelian bosonization and renormalization group (RG) arguments to derive an effective 0(4)-symmetric nonlinear u model in D=2+1 for the case when both interstripe couplings are of equal magnitude as well as equally RG relevant. By studying the effects of various symmetry lowering perturbations, We determine the structure of the phase diagram and show that, in general, it has a broad regime in which both orders coexist. The quantum and thermal critical behavior is discussed in detail, and the phase coexistence region is found to end at associated T=0 as well as T> 0 tetracritical points. The possible role of hedgehog topological excitations of the theory is considered and argued to be RG irrelevant at the spatially anisotropic higher dimensional low-energy fixed point theory. Our results are also relevant to the case of competing Neel and valence bond solid orders in quantum magnets on two-dimensional isotropic square as well as rectangular lattices interacting via nearest-neighbor Heisenberg exchange interactions.
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