Single-worldline theory for a dissipative Mott transition
In one dimension at zero temperature, local baths with spectral exponent $s$ can stabilize a compressible, non-superfluid dissipative phase between the Mott insulator and Luttinger liquid. The dissipative-to-Mott transition is accessible neither to perturbative renormalization-group methods nor to the free-fermion description of the conventional Mott transition. Here, we show it is governed by the worldline of a single doped excitation, whose geometrical roughness determines the critical exponents. Without dissipation, this worldline undergoes Brownian motion, recovering $\beta=\nu=1/z=1/2$. Dissipation turns it into a long-range interacting interface, yielding continuously varying exponents $\beta=\nu=1/z=s-1$ for $1<s<3/2$, and $\beta=\nu=1/z=0$ for $s<1$. The same theory identifies $s=3/2$ as the threshold above which the dissipative phase disappears. Large-scale Monte Carlo simulations of both the single-worldline theory and the original many-body model quantitatively support these predictions.