Positivity of $|p|^a|q|^b+|q|^b|p|^a$

Li Chen, Heinz Siedentop

Published 2013-01-08, updated 2013-03-20Version 2

We show that $$J_{a,b,n}:=\frac12(|p|^a|q|^b+|q|^b|p|^a)$$ is positive, if $n\geq b+a$. (Here $q$ is the multiplication by $x$ and $p:= \mathrm{i}^{-1}\nabla$.) Furthermore we show that it generalizes the generalized Hardy inequalities for the fractional Laplacians.