($s=2$). These two sectors are decoupled and can be studied separately. We find, that while the plasmon mode is gapped out at small wave-numbers due to the interaction induced resistivity (see Fig. \[fig:Fig\_collective\_charge\_re\]), a so-called second sound mode, corresponding to a wavelike propagation of energy, appears (Fig. \[fig:Fig\_collective\_energy\_re\]). Diffusive modes, corresponding to the diffusion of charge, heat and quasiparticles were found (see Figs. \[fig:Fig\_collective\_charge\_im\], \[fig:Fig\_collective\_energy\_im\_Small\_q\]). Their dispersion relations were calculated and showed to agree with known results [@Briskot2015; @Torre2019; @Phan2013]. Besides these well studied modes, an infinite set of damped modes connected to excitations in higher angular harmonic channels was found (see Figs. \[fig:Fig\_collective\_charge\_im\], \[fig:Fig\_collective\_energy\_im\]). The dispersions of these modes are purely imaginary at vanishing wave-numbers and approach in the long wavelength limit the values $\omega_{m}\left(q=0\right)=-i/\tau_{\varepsilon/c,m}$ for the $m$-th angular harmonic in the energy ($\varepsilon$) or the charge ($c$) channels. At finite wave-numbers, these modes show a complex structure of merging branches. Similar modes play an important role in the equilibration of unitary fermi gases [@Brewer2015] and the QCD plasma [@Romatschke2016; @Romatschke2018; @Heller2018]. They also determine the unusual phase space dynamics of graphene electrons which was the subject of an earlier work [@Kiselev2019b].

Theoretical framework\[sec:Theoretical-framework\]
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Kinetic equation\[subsec:Kinetic-equation\_QB\_Graphene\]
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In 