Absence of a gap in the Gaffnian state
Résumé
We study the Gaffnian trial wavefunction proposed to describe fractional quantum Hall correlations at Bose filling factor ν=2/3ν=2/3\nu=2/3 and Fermi filling ν=2/5ν=2/5\nu=2/5. A family of Hamiltonians interpolating between a hard-core interaction for which the physics is known and a projector whose ground state is the Gaffnian is studied in detail. We give evidence for the absence of a gap by using large-scale exact diagonalizations in the spherical geometry. This is in agreement with recent arguments based on the fact that this wavefunction is constructed from a non-unitary conformal field theory. By using the cylinder geometry, we discuss in detail the nature of the underlying minimal model and we show the appearance of heterotic conformal towers in the edge energy spectrum where left and right movers are generated by distinct primary operators.