  We present a bosonic model, in which two bosons may form a bound pair with
d-wave symmetry via the four-site ring exchange interaction. A d-wave pairing
superfluid as well as a d-wave density wave (DDW) state, are proposed to be
achievable in this system. This exotic bosonic system can be realized in the
BEC zone of a two-dimensional attractive p-band spinless fermionic system. By
the mean field approach, we find that at low densities, the d-wave pairs may
condensate, leading to a d-wave bosonic paired superfluid. At some particular
filling factors, a novel phase, d-wave density wave state, emerges. We study
this DDW state and its corresponding quantum phase transition in a two-leg
ladder by the time-evolving block decimation (TEBD) method.
