A ring of N identical phase oscillators with nonlocal coupling:
θ̇k = ω + (K/P) Σ|k-j|≤R sin(θj−θk−α)
Despite all oscillators being identical, chimera states spontaneously break the symmetry: a synchronized cluster coexists with an incoherent one.
Discovered by Kuramoto & Battogtokh (2002), named by Abrams & Strogatz (2004).