Universal Rényi entanglement entropy of quasiparticle excitations

The R\'enyi entropies of quasiparticle excitations in the many-body gapped systems show a remarkable universal picture which can be understood partially by combination semiclassical argument with quantum effect (in)distinguishability. are independent model, momenta, and connectedness subsystem. In this letter we calculate exactly single-interval double-interval fermions, bosons, XY chains. We find additional contributions to entropy excited states quasiparticles different momenta. terms fermionic bosonic chains, depend on momentum differences quasiparticles, for single interval double interval. derive analytical extremely limit, matching perfectly numerical results as long either intrinsic correlation length model or all de Broglie wavelengths small. When difference any pair distinct is small, non-negligible. On contrary, when momenta each large, could neglected. its chain same those chain, while intervals different, due fact that local degrees freedom Pauli matrices not spinless fermions. argue derived formulas have properties applied wider range models than discussed here.