R. Haussmann et al., CORRELATION-ENERGY AND TUNNELING DENSITY-OF-STATES IN THE FRACTIONAL QUANTUM HALL REGIME, Physical review letters, 76(6), 1996, pp. 979-982
We report on an exact sum rule for the tunneling density of states of
a two-dimensional electron system in a strong magnetic field. Assuming
the well-defined gap (Delta) discovered in recent experiments, the su
m rules imply that Delta is proportional to the ground state correlati
on energy. Our results provide a quantitative explanation for the size
of the measured gap and demonstrate that tunneling experiments can be
used to measure the correlation energy.