Is inertial-range intermittency of superfluid turbulence the same as classical?
In plain words
Above about one kelvin, superfluid helium is a mixture of a superfluid and a normal fluid, and its turbulence shows the same average spectrum as water. Whether its rare violent fluctuations are also the same at every temperature is disputed.
Precise statement
In quasiclassical turbulence of 4He between about 1.2 K and $T_{\lambda}=2.17\,\mathrm{K}$, are the inertial-range velocity structure-function exponents $\zeta_p$ equal to the classical values for all superfluid fractions $\rho_s/\rho$, or does intermittency change where $\rho_s/\rho$ is small or close to 1? Answer: $\zeta_p(T)$ for p up to 6 with error bars.
What would settle it
Probe measurements with characterized response resolving inertial-range increments at several temperatures in one flow, compared with two-fluid simulations.
Status in the literature
Simulations since about 2013 report temperature-dependent intermittency, while probe experiments (about 2017) find none; the disagreement is unresolved.