Is there a canonical way of lifting a vector field $X$ on $M$ to its tangent bundle $TM$?
Is there a canonical way of lifting vector field $X$ on $M$ to its tangent bundle $TM$?
I came up with this question while studying tangent bundle formalism of Lagrangian mechanics. In Lagrangian mechanics, a vector field on $X$ on $M$ may represent a continuous symmetry, and since the Lagrangian function is defined on $TM$, we want to lift $X$ to a vector field in $TM$. Is there a canonical way to do this?
A vector field on $M$ is a section $M\rightarrow TM$. There exists an embedding $V:TM\rightarrow TTM$ such that for every function $f$ defined on $TM$, and any vector field $X$, $V(X)(f)(x,u)={d\over{dt}}_{t=0}f(x,u+tX)$.
https://en.wikipedia.org/wiki/Double_tangent_bundle#Canonical_tensor_fields_on_the_tangent_bundle
Let $M$ be a differentiable manifold (in the context of lagrangian mechanics, you can see $M$ as the space of all possible positions of the system). Suppone that on $M$ lagrangian coordinates $q=(q^j)$ are defined. A vector field $X$ on $M$ can be written as $$X = X^j(q) \frac{\partial}{\partial q^j}$$ where $X^j$ is the $j$-th component of $X$. Then the lifting of $X$ is the vector field on $TM$ defined by $$X^T= X^j(q) \frac{\partial}{\partial q^j} + (\frac{d}{dt}X^j(q)) \frac{\partial}{\partial \dot{q^j}}. $$