We perform numerical simulations of the SU(2) Boltzmann-Vlasov equation including both hard elastic particle collisions and soft interactions mediated by classical Yang-Mills fields. Using this technique we calculate the momentum-space broadening of high-energy jets in real time for both locally isotropic and anisotropic plasmas. In both cases we introduce a separation scale that separates hard and soft interactions and demonstrate that our results for jet broadening are independent of the precise separation scale chosen. For an isotropic plasma this allows us to calculate the jet transport coefficient $\widehat{q}$ including hard and soft nonequilibrium dynamics. For an anisotropic plasma the jet transport coefficient becomes a tensor with ${\widehat{q}}_L\ne {\widehat{q}}_{\perp }$. We find that for weakly coupled anisotropic plasmas the fields develop unstable modes, forming configurations where $B_{\perp }>E_{\perp }$ and $E_z>B_z$, which lead to ${\widehat{q}}_L>{\widehat{q}}_{\perp }$. We study whether the effect is strong enough to explain the experimental observation that high-energy jets traversing the plasma perpendicular to the beam axis experience much stronger broadening in rapidity, $\Delta \eta$, than in azimuth, $\Delta \varphi$.

• Received 15 October 2007

DOI:https://doi.org/10.1103/PhysRevC.78.024909