We show that for entire maps of the form z ↦ λexp(z) such that the orbit of zero is bounded and Lebesgue almost every point is transitive, no absolutely continuous invariant probability measure can exist. This answers a long-standing open problem.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-fm198-3-6, author = {Neil Dobbs and Bart\l omiej Skorulski}, title = {Non-existence of absolutely continuous invariant probabilities for exponential maps}, journal = {Fundamenta Mathematicae}, volume = {201}, year = {2008}, pages = {283-287}, zbl = {1167.37024}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-fm198-3-6} }
Neil Dobbs; Bartłomiej Skorulski. Non-existence of absolutely continuous invariant probabilities for exponential maps. Fundamenta Mathematicae, Tome 201 (2008) pp. 283-287. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-fm198-3-6/