We prove that every generator of a symmetric contraction semigroup on a -finite measure space admits, for , a Hörmander-type holomorphic functional calculus on in the sector of angle . The obtained angle is optimal.
Andrea Carbonaro. Oliver Dragičević. "Functional calculus for generators of symmetric contraction semigroups." Duke Math. J. 166 (5) 937 - 974, 1 April 2017. https://doi.org/10.1215/00127094-3774526