  Let $\mathbb{G}$ be a split connected reductive group scheme over the ring of
integers $\mathfrak{o}$ of a finite extension $L|\mathbb{Q}_p$ and $\lambda\in
X(\mathbb{T})$ an algebraic character of a split maximal torus
$\mathbb{T}\subseteq\mathbb{G}$. Let us also consider $X^{\text{rig}}$ the
rigid analytic flag variety of $\mathbb{G}$ and $G=\mathbb{G}(L)$. In the first
part of this paper, we introduce a family of $\lambda$-twisted differential
operators on a formal model $\mathfrak{Y}$ of $X^{\text{rig}}$. We compute
their global sections and we prove coherence together with several
cohomological properties. In the second part, we define the category of
coadmissible $G$-equivariant arithmetic $\mathcal{D}(\lambda)$-modules over the
family of formal models of the rigid flag variety $X^{\text{rig}}$. We show
that if $\lambda$ is such that $\lambda + \rho$ is dominant and regular ($\rho$
being the Weyl character), then the preceding category is anti-equivalent to
the category of admissible locally analytic $G$-representations, with central
character $\lambda$. In particular, we generalize the results of
Huyghe-Patel-Strauch-Schmidt for algebraic characters (cf. [25] in the text).
