  We present a measurement of the transverse momentum with respect to the jet
axis ($k_{T}$) of particles in jets produced in $p\bar p$ collisions at
$\sqrt{s}=1.96$ TeV. Results are obtained for charged particles within a cone
of opening angle 0.5 radians around the jet axis in events with dijet invariant
masses between 66 and 737 GeV/c$^{2}$. The experimental data are compared to
theoretical predictions obtained for fragmentation partons within the framework
of resummed perturbative QCD using the modified leading log and
next-to-modified leading log approximations. The comparison shows that trends
in data are successfully described by the theoretical predictions, indicating
that the perturbative QCD stage of jet fragmentation is dominant in shaping
basic jet characteristics.
