Instabilities in non-expanding glasma

A homogeneous color magnetic field is known to be unstable for the fluctuations perpendicular to the field in the color space (the Nielsen–Olesen instability). We argue that these unstable modes, exponentially growing, generate an azimuthal magnetic field with the original field being in the z-direction, which causes the Nielsen–Olesen instability for another type of fluctuations. The growth rate of the latter unstable mode increases with the momentum pz and can become larger than the former's growth rate which decreases with increasing pz. These features may explain the interplay between the primary and secondary instabilities observed in the real-time simulation of a non-expanding glasma, i.e., stochastically generated anisotropic Yang–Mills fields without expansion.