Do chaotic field lines cause fast reconnection in coronal loops?*

The footpoints of coronal loops are constantly shuffled by convection on the solar surface, entangling the magnetic field lines. According to Parker's coronal heating model, the entanglement of field lines gives rise to the formation of intense current sheets. These sheets are responsible for the reconnection of magnetic field lines, resulting in the conversion of magnetic energy into plasma energy. We investigate how coronal loops with entangled field lines evolve from a quasi-static state to a dynamic state through a series of reduced magnetohydrodynamic simulations. The simulations reveal that as the Lundquist number increases, the intensity of current sheets also amplifies. Additionally, it is observed that when the Lundquist number is sufficiently high, the current sheets become prone to tearing instability despite the stabilizing effects of line-tying boundary conditions. Using a suite of diagnostics, including parallel voltage, squashing factors of the field line mapping, and field line velocity, we address whether the chaotic separation of neighboring field lines causes fast reconnection, as has been suggested in some recent studies. We find that chaotic field line separation dramatically enhances the field line velocity to extremely high values for field lines of high squashing factors. However, the field line velocity appears to be an unreliable measure of the reconnection rate. In comparison, the parallel voltage, which is directly related to the current density, is a better metric.