Let A be a linear closed one-to-one operator in a complex Banach space X, having dense domain and dense range. If A is of type ω (i.e.the spectrum of A is contained in a sector of angle 2ω, symmetric about the real positive axis, and is bounded outside every larger sector), then A has a bounded functional calculus in the real interpolation spaces between X and the intersection of the domain and the range of the operator itself.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-sm145-1-5, author = {Giovanni Dore}, title = {$H^{$\infty$}$ functional calculus in real interpolation spaces, II}, journal = {Studia Mathematica}, volume = {147}, year = {2001}, pages = {75-83}, zbl = {0985.47015}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm145-1-5} }
Giovanni Dore. $H^{∞}$ functional calculus in real interpolation spaces, II. Studia Mathematica, Tome 147 (2001) pp. 75-83. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm145-1-5/