  We present a theoretical description of the dynamics of a semi-flexible
polymer being pulled through a nanopore by an external force acting at the
pore. Our theory is based on the tensile blob picture of Pincus in which the
front of the tensile force propagates through the backbone of the polymer, as
suggested by Sakaue and recently applied to study a completely flexible polymer
with self-avoidance, by Dubbledam et al. For a semi-flexible polymer with a
persistence length P , its statistics is self-avoiding for a very long chain.
As the local force increases, the blob size starts to decrease. At the blob
size P/a^2 , where a is the size of a monomer, the statistics becomes that of
an ideal chain. As the blob size further decreases to below the persistence
length P, the statistics is that of a rigid rod. We argue that semi-flexible
polymer in translocation should include the three regions: a self-avoiding
region, an ideal chain region and a rigid rod region, under uneven tension
propagation, instead of a uniform scaling picture as in the case of a
completely flexible polymer. In various regimes under the effect of weak,
intermediate and strong driving forces we derive equations from which we can
calculate the translocation time of the polymer. The translocation exponent is
given by \alpha=1+\mu, where \mu is an effective exponent for the end-to-end
distance of the semi-flexible polymer, having a value between 1/2 and 3/5,
depending on the total contour length of the polymer. Our results are of
relevance for forced translocation of biological polymers such as DNA through a
nanopore.
