Influence of tearing instability on magnetohydrodynamic turbulence

It has been proposed recently by Loureiro & Boldyrev (2017) and Mallet et al. (2017) that current sheets formed in the inertial range of magnetohydrodynamic turbulence become affected by the tearing instability at scales smaller than a critical scale $\lambda_\mathrm{c}$, larger than the dissipation scale of turbulence. If true, this process can modify the nature of energy cascade at smaller scales, leading to a new, tearing-mediated regime of MHD turbulence. In this Letter we present a numerical study of strongly anisotropic turbulent eddies and demonstrate that tearing instability can indeed compete with their nonlinear evolution. The results therefore provide the first direct numerical support for the picture that a new regime of MHD turbulence can exist below $\lambda_\mathrm{c}$.