Bound to bounce: a coupled scalar-tachyon model for a smooth
  bouncing/cyclic universe
  We introduce a string-inspired model for a bouncing/cyclic universe,
utilizing the scalar-tachyon coupling as well as contribution from curvature in
a closed universe. The universe undergoes the locked inflation, tachyon matter
dominated rolling expansion, turnaround and contraction, as well as the
subsequent deflation and "bounce" in each cycle of the cosmological evolution.
We perform extensive analytic and numerical studies of the above evolution
process. The minimum size of the universe is nonzero for generic initial
values. The smooth bounce are made possible because of the negative
contribution to effective energy density by the curvature term. No ghosts are
ever generated at any point in the entire evolution of the universe, with the
Null, Weak, and Dominant Energy Conditions preserved even at the bounce points,
contrary to many bounce models previously proposed. And the Strong Energy
Condition is satisfied in periods with tachyon matter domination.
