Structure of the cuspidal rational torsion subgroup of J_1(p^n)
  In this article, we determine the structure of the $p$-primary subgroup of the cuspidal rational torsion subgroup of the Jacobian $J_1(p^n)$ of the modular curve $X_1(p^n)$ for a regular prime $p$. 
Yifan Yang, Jeng-Daw Yu