Improved endpoint bounds for the lacunary spherical maximal operator

Abstract

We prove new endpoint bounds for the lacunary spherical maximal operator and as a consequence obtain almost everywhere pointwise convergence of lacunary spherical means for functions locally in $L\log\log\log L(\log\log\log\log L)^{1+\epsilon}$ for any $\epsilon>0$.Comment: 27 pages, 3 figure