A noncommutative weak $L_1$-estimate for rough singular integrals

In this paper, we establish a noncommutative version of Andreas Seeger’s weak type $(1,1)$ estimate for singular integral operators with kernels satisfying angular $L\log L$ integrability and an averaged radial Dini condition. The strategy for obtaining the sharp integrability condition involves not only some new estimates of the off-diagonal good and bad functions in Parcet’s noncommutative Calderón-Zygmund decomposition but also certain essential modifications of Seeger’s kernel decomposition and estimates.