arXiv:1307.7719 · Physical Review B
Susceptibility at the superfluid-insulator transition for one-dimensional disordered bosons
Shankar Iyer, David Pekker, Gil Refael
Abstract
A pair of recent Monte Carlo studies have reported evidence for and against a crossover from weak- to strong-disorder criticality in the one-dimensional dirty boson problem. The Monte Carlo analyses rely on measurement of two observables: the effective Luttinger parameter ${K}_{\mathrm{eff}}$ and the superfluid susceptibility $\ensuremath{\chi}$. The former quantity was previously calculated analytically, using the strong-disorder renormalization group (SDRG), by Altman, Kafri, Polkovnikov, and Refael. Here, we use an extension of the SDRG framework to find a nonuniversal anomalous dimension ${\ensuremath{\eta}}_{\mathrm{sd}}$ characterizing the divergence of the susceptibility with system size, $\ensuremath{\chi}\ensuremath{\sim}{L}^{2\ensuremath{-}{\ensuremath{\eta}}_{\mathrm{sd}}}$. We show that ${\ensuremath{\eta}}_{\mathrm{sd}}$ obeys the hyperscaling relation ${\ensuremath{\eta}}_{\mathrm{sd}}=1/2{K}_{\mathrm{eff}}$. We also identify an important obstacle to measuring this exponent on finite-size systems and comment on the implications for numerics and experiments.