Torsion Subgroups of Modular Jacobians

par Elvira Lupoian

jeudi 15 janv. 2026, 14:00 → 15:00 Europe/Paris

In 1977 Mazur proved that the rational torsion subgroup of the Jacobian of the modular curve X_0( N), N > 5 prime, is generated by the linear equivalence class of the difference of the two cusps. More generally, it is conjectured that for a general N, the rational torsion subgroup of the Jacobian of X_0( N) is generated by cusps.  In this talk, we'll discuss a generalisation of this to other modular curves, namely certain covers of X_0( N), indexed by subgroups of (Z/NZ)^*.