  We investigate the statistical mechanics of long developable ribbons of
finite width and very small thickness. The constraint of isometric deformations
in these ribbon-like structures that follows from the geometric separation of
scales introduces a coupling between bending and torsional degrees of freedom.
Using analytical techniques and Monte Carlo simulations, we find that the
tangent-tangent correlation functions always exhibits an oscillatory decay at
any finite temperature implying the existence of an underlying helical
structure even in absence of a preferential zero-temperature twist. In addition
the persistence length is found to be over three times larger than that of a
wormlike chain having the same bending rigidity. Our results are applicable to
many ribbon-like objects in polymer physics and nanoscience that are not
described by the classical worm-like chain model.
