Nonstandard transitions in the Kuramoto model: A role of asymmetry in natural frequency distributions

TL;DR

This paper investigates how asymmetry in natural frequency distributions affects bifurcation diagrams in the Kuramoto model, revealing two novel transition types using analytical and simulation methods.

Contribution

It introduces two nonstandard bifurcation diagrams caused by asymmetry and bimodality, expanding understanding of transition phenomena in the Kuramoto model.

Findings

Asymmetry leads to two distinct bifurcation diagrams.

Bimodality in frequency distribution influences transition types.

First diagram shows standard and discontinuous transitions; second reveals oscillatory states.

Abstract

We study transitions in the Kuramoto model by shedding light on asymmetry in the natural frequency distribution, which has been assumed to be symmetric in many previous studies. The asymmetry brings two nonstandard bifurcation diagrams, with the aid of bimodality. The first diagram consists of stationary states, and has the standard continuous synchronization transition and a subsequent discontinuous transition as the coupling strength increases. Such a bifurcation diagram has been also reported in a variant model, which breaks the odd symmetry of the coupling function by introducing the phase lag. The second diagram includes the oscillatory state emerging from the partially synchronized state and followed by a discontinuous transition. This diagram is firstly revealed in this study. The two bifurcation diagrams are obtained by employing the Ott-Antonsen ansatz, and are verified by direct $N$-body simulations. We conclude that the asymmetry in distribution, with the bimodality, plays a similar role to the phase lag, and diversifies the transitions.