Collective Non-Abelian Instabilities in a Melting Color Glass Condensate

We present first results for ($3+1$)D simulations of SU(2) Yang-Mills equations for matter expanding into the vacuum after a heavy ion collision. Violations of boost invariance cause a non-Abelian Weibel instability leading soft modes to grow with proper time $\tau$ as $\exp (\Gamma \sqrt{g^2\mu \tau })$, where $g^2\mu$ is a scale arising from the saturation of gluons in the nuclear wave function. The scale for the growth rate $\Gamma$ is set by a plasmon mass, defined as ${\omega }_{\mathrm{pl}}={\kappa }_0\sqrt{g^2\mu /\tau }$, generated dynamically in the collision. We compare the numerical ratio $\Gamma /{\kappa }_0$ to the corresponding value predicted by the hard thermal loop formalism for anisotropic plasmas.