The disorder-induced quantum phase transition between superfluid and
non-superfluid states of bosonic particles in one dimension is generally
expected to be of the Berezinskii-Kosterlitz-Thouless (BKT) type. Here, we show
that hard-core lattice bosons with integrable power-law hopping decaying with
distance as 1/rα - corresponding in spin language to a XY model with
power-law couplings - undergo a non-BKT continuous phase transition instead. We
use exact quantum Monte-Carlo methods to determine the phase diagram for
different values of the exponent α, focusing on the regime α>2.
We find that the scaling of the superfluid stiffness with the system size is
scale-invariant at the transition point for any α≤3 - a behavior
incompatible with the BKT scenario and typical of continuous phase transitions
in higher dimension. By scaling analysis near the transition point, we find
that our data are consistent with a correlation length exponent satisfying the
Harris bound ν≥2 and demonstrate a new universal behavior of
disordered bosons in one dimension. For α>3 our data are consistent with
a BKT scenario where the liquid is pinned by infinitesimal disorder