  We study the locally analytic vectors in the completed cohomology of modular
curves and determine the eigenvectors of a rational Borel subalgebra of
$\mathfrak{gl}_2(\mathbb{Q}_p)$. As applications, we prove a classicality
result for overconvergent eigenforms of weight one and give a new proof of the
Fontaine-Mazur conjecture in the irregular case under some mild hypotheses. For
an overconvergent eigenform of weight $k$, we show its corresponding Galois
representation has Hodge-Tate-Sen weights $0,k-1$ and prove a converse result.
