New formula for $\ln(e^Ae^B)$ in terms of commutators of $A$ and $B$
Matematičeskie zametki, Tome 23 (1978) no. 6, pp. 817-824
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We establish the formula
$$
\ln(e^Be^A)=\int_0^t\psi(e^{-\tau ad_A}e^{-\tau ad_B})e^{-\tau ad_A}\,d\tau(A+B),
$$
where $\psi(x)=(\ln x)/(x-1)$; here $A$ and $B$ are elements of a. finite-dimensional Lie algebra which satisfy certain conditions. This formula enables us, in particular, to give a simple proof of the Campbell–Hausdorff theorem. We also give a generalization of the formula to the case of an arbitrary number of factors.
@article{MZM_1978_23_6_a3,
author = {M. V. Mosolova},
title = {New formula for $\ln(e^Ae^B)$ in terms of commutators of $A$ and $B$},
journal = {Matemati\v{c}eskie zametki},
pages = {817--824},
publisher = {mathdoc},
volume = {23},
number = {6},
year = {1978},
language = {ru},
url = {http://geodesic.mathdoc.fr/item/MZM_1978_23_6_a3/}
}
M. V. Mosolova. New formula for $\ln(e^Ae^B)$ in terms of commutators of $A$ and $B$. Matematičeskie zametki, Tome 23 (1978) no. 6, pp. 817-824. http://geodesic.mathdoc.fr/item/MZM_1978_23_6_a3/