whose scattering rates are enhanced by a large factor of $\log\left(1/\alpha\right)$. Here, the velocities of the interacting particles are parallel to each other. Due to the linear graphene spectrum, all particles travel at the same speed, regardless of their momentum. Particles traveling in parallel have a particularly long time to interact with each other, hence the strong enhancement. Transport in the hydrodynamic regime, however, is dominated by processes, which have the smallest scattering rates (for details see Eq. (\[eq:Collinear\_non\_collinear\_separation\]) and below). Such “slow” processes are represented by collinear zero modes – functions that set the collinear part of the collision operator to zero [@Fritz2008; @Kashuba2008].

We solve the kinetic equation by reducing it to a matrix equation in the space of collinear zero modes $\chi_{\mathbf{k},\lambda}^{\left(m,s\right)}=\lambda^{m}e^{im\theta}\left\{ 1,\lambda,\lambda\beta v\hbar k\right\} $ (see Sec. \[subsec:Collinear-zero-modes\]). Here, $\theta$ is the polar angle and $k$ the modulus of the momentum variable $\mathbf{k}$, $\lambda=\pm1$ is the band index, $m$ labels the angular harmonics $\exp\left(im\theta\right)$, and $s\in\left\{ 1,2,3\right\} $ labels the three basis functions written in curly brackets. To an excellent approximation, it is sufficient to retain only the $s=1$ and $s=3$ modes. These modes describe charge ($c$) and energy ($\varepsilon$) excitations, respectively. A numerical evaluation of 