Origin of the residual growth-rate discrepancy

Identify the physical origin of the remaining discrepancy between the analytical relativistic tearing-instability growth-rate predictions and the PIC simulation results, including the possible role of finite-Larmor-radius effects, and establish a consensus explanation.

Background

The revised extrapolated-A approximation improves the prediction of the most unstable wavenumber, but the theoretical growth-rate curves still require an empirical multiplicative factor for comparison with PIC simulations. The paper notes that this mismatch may result from finite-Larmor-radius effects omitted from the analytical treatment, while acknowledging that other explanations have also been proposed. The authors explicitly state that no consensus has been reached regarding the cause.

References

This discrepancy may be attributable to finite-Larmor-radius effects not included in the theory. Although several possible origins of this discrepancy have been proposed, no consensus has yet been reached.

— Revisiting the Growth Rate of the Relativistic Tearing Instability: The Role of the Non-ideal MHD Structure  (2608.19645 - Sugimoto et al., 20 Aug 2026) in Section 3, discussion following Fig. 2