Langevin-type dynamics and hypocoercivity on $\mathrm{SE}(3)$
We construct hypocoercive Kolmogorov-type operators on the Euclidean motion group $\mathrm{SE}(3)=\mathbb{R}^3\rtimes\mathrm{SO}(3)$ using ZXZ Euler angles and study their long-time behaviour using the abstract hypocoercivity method. The operator $L=S-A$ decomposes into a symmetric part $S$, corresponding to a degenerate diffusion on the rotation component $\mathrm{SO}(3)$, and an antisymmetric part $A$, which captures transport and torque effects induced by the Lie group structure. The associated invariant probability measure is $μ_Φ=γ_Φ\otimesν_3$, where $γ_Φ$ is a probability measure on $\mathbb{R}^3$ with density $Z(Φ)^{-1}e^{-Φ}$ with respect to the Lebesgue measure, and $ν_3$ is the normalized Haar measure on $\mathrm{SO}(3)$. As a consequence, if $Φ\in C^\infty(\mathbb{R}^3)$ is bounded from below, $γ_Φ$ satisfies a Poincaré inequality with constant $Λ>0$, and there exists $c<\infty$ such that \begin{equation*} |\nabla_ξ^2Φ(ξ)| \leq c\bigl(1+|\nabla_ξΦ(ξ)|\bigr), \quad ξ\in\mathbb{R}^3, \end{equation*} then the semigroup generated by the closure of $L$ converges exponentially fast to equilibrium in $L^2(\mathrm{SE}(3),μ_Φ)$.