  In a strongly magnetized, magnetically dominated relativistic plasma,
Alfv\'enic turbulence can extend to scales much smaller than the particle
inertial scales. It leads to an energy cascade somewhat analogous to inertial-
or kinetic-Alfv\'en turbulent cascades existing in non-relativistic space and
astrophysical plasmas. Based on phenomenological modeling and particle-in-cell
numerical simulations, we propose that the energy spectrum of such relativistic
kinetic-scale Alfv\'enic turbulence is close to $k^{-3}$ or slightly steeper
than that due to intermittency corrections or Landau damping. We note the
analogy of this spectrum with the Kraichnan spectrum corresponding to the
enstrophy cascade in 2D incompressible fluid turbulence. Such turbulence
strongly energizes particles in the direction parallel to the background
magnetic field, leading to nearly one-dimensional particle momentum
distributions. We find that these distributions have universal log-normal
statistics.
