A noncommutative maximal inequality for Fej\'{e}r means on totally disconnected non-abelian groups

Abstract

In this paper, we explore Fourier analysis for noncommutative $L_p$ space-valued functions on $G$, where $G$ is a totally disconnected non-abelian compact group. By additionally assuming that the value of these functions remains invariant within each conjugacy class, we establish a noncommutative maximal inequality for Fej\'er means utilizing the associated character system of $G$. This is an operator-valued version of the classical result due to G\'at. We follow essentially the classical sketch, but due to the noncommutativity, many classical arguments have to be revised. Notably, compared to the classical results. the bounds of our estimates are explicity calculated.