Surprise! Tax cuts for the rich lead to higher income inequality, but "do not have any significant effect on economic growth and unemployment."
Evidence for 18 OECD countries over the last 50 years in this paper:

The empirical evidence is mounting: trickle-down economics doesn't work. In a recent paper, @SGechert and I analyse 441 estimates from 42 studies to show that there's no (!) evidence that corporate tax cuts boost growth once we correct for publication bias

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