Canonical one-form on a cotangent bundle
= Canonical one-form on a cotangent bundle
{title2=$\lambda$}
= Tautological one-form
{synonym}
= Canonical one-forms on cotangent bundles
{synonym}
For the <cotangent bundle> projection $\pi:T^*X\to X$, the canonical <differential one-form> is $\lambda_{(x,\xi)}(v)=\xi(d\pi(v))$. In coordinates it is $\sum_j\xi_jdx_j$. The canonical <symplectic form> is $-d\lambda$ in the position-first convention $\sum_jdx_j\wedge d\xi_j$.