Dynamical structure factor of the SU(4) algebraic spin liquid on the honeycomb lattice

We compute the momentum-resolved dynamical spin structure factor S(k, omega) of the SU(4) Heisenberg model on the honeycomb lattice assuming the pi-flux Dirac spin liquid ground state by using two methods: (i) variation-ally using Gutzwiller projected particle-hole excitations of the pi-flux Fermi sea, and (ii) in the noninteracting parton mean-field picture. The two approaches produce qualitatively similar results. Based on this analogy, we argue that the energy spectrum of the projected excitations is a gapless continuum of fractional excitations. Quantitatively, the Gutzwiller projection shifts the weight from higher to lower energies, thus emphasizing the lower edge of the continuum. In the mean-field approach, we obtained the 1/distance4 decay of the spin correlation function, and the local correlations show S33MF(omega) oc omega 3 behavior.