  We investigate the low energy physics of particles in the symmetric phase of
the N=6 mass-deformed ABJM theory in terms of the superconformal
nonrelativistic field theory with 14 supercharges. They describe the certain
kind of excitations on M2 branes in the background of external four-form flux.
We study the nonrelativistic superconformal algebra and their representations
by using the operator-state correspondence with the related harmonic oscillator
Hamiltonian. We find the unitarity bounds on the scaling dimension and particle
number of any local operator, and comment on subtleties in computing the
superconformal Witten index that counts the chiral operators.
