Sharp character bounds and cutoff profiles for symmetric groups

Abstract: We develop a flexible technique to estimate the characters of symmetric groups, via the Murnaghan--Nakayama rule, the Larsen--Shalev character bounds, the Naruse hook length formula, and appropriate diagram slicings. This allows us to prove sharp character bounds as well as asymptotic equivalents for characters of low-level representations. We also prove an optimal uniform character bound. As a result, we prove under a mild condition on the support size that random walks on symmetric groups generated by a conjugacy class exhibit a total variation and $L^2$ cutoff and find their cutoff profiles.