The collective behavior of the $\mathrm{SL}(2,\mathbb{R})$ covariant brane states of noncritical $c=1$ string theory, found in a previous work, is studied in the Fermi liquid approximation. It is found that such states mimic the coset WZW model, whereas only by further restrictions one recovers the double-scaling limit which was purported to be equivalent to closed string models. Another limit is proposed, inspired by the tachyon condensation ideas, where the spectrum is the same of two-dimensional string theory. We close by noting some strange connections between vacuum states of the theory in their different interpretations.

• Received 27 March 2008

DOI:https://doi.org/10.1103/PhysRevD.78.024028