  The study of jets in heavy-ion collisions provides important information
about the interaction of partons with the medium that they traverse. The seeds
of jets are highly energetic partons, which are produced from hard scatterings
during the collision event. As such, they are affected by all different stages
of the medium's time evolution, including the glasma, which is the
pre-equilibrium precursor state of the quark-gluon plasma. Here we report on
our numerical lattice simulations of partons traversing the boost-invariant,
non-perturbative glasma as created at the early stages of collisions at RHIC
and LHC. We find that partons quickly accumulate transverse momentum up to the
saturation momentum during the glasma stage. Furthermore, we observe an
interesting anisotropy in transverse momentum broadening of partons with larger
broadening in the rapidity than in the azimuthal direction. Its origin can be
related to correlations among the longitudinal color-electric and
color-magnetic flux tubes in the initial state of the glasma. We compare these
observations to the semi-analytic results obtained by a weak-field
approximation, where we also find such an anisotropy in a parton's transverse
momentum broadening.
