  Super-Efimov states are a new kind of universal three-body bound states
predicted for three identical fermions with $p$-wave resonant interactions in
two dimensions by a recent field-theoretic calculation
[Phys.~Rev.~Lett.~\textbf{110}, 235301 (2013)]. The binding energies of these
states obey a dramatic double exponential scaling $E_n=E_*\exp(-2 e^{\pi
n/s_0+\theta})$ with universal scaling $s_0=4/3$ and three-body parameters
$E_*$ and $\theta$. We use the hyperspherical formalism and show that the
super-Efimov states originate from an emergent effective potential
$-1/4\rho^2-(s_0^2+1/4)/\rho^2\ln^2\left(\rho\right)$ at large hyperradius
$\rho$. Moreover, for pairwise interparticle potentials with van der Waals
tails, our numerical calculation indicates that the three-body parameters $E_*$
and $\theta$ are also universal and the ground super-Efimov state shall cross
the threshold when the $2$D $p$-wave scattering area is about $-42.0\,
l_\text{vdW}^2$ with $l_\text{vdW}$ the van der Waals length.
