The article is "The Top One Percent in International and Historical Perspective." It appeared in Journal of Economic Perspectives, Vol. 27, Number 3, Summer 2013. The authors (Facundo Alverado, Anthony B. Atkinson, Thomas Piketty, and Emmanuel Saez) show that the dramatic increase in the top 1% of earners in the United States is correlated with a decrease of taxes by that same group. Other countries (the UK) show a similar correlation. Industrialized and Anglo-Saxon countries which did not show a decrease in taxing on the top 1% did not show as dramatic a rise in top 1% earnings. This suggests a correlation between decreased taxes on the top 1% and increased earnings. The countries which showed less decreases in taxes of the top income shares showed less increases in earnings. This suggests that tax cuts for the rich do not lead to that money "trickling down" to the middle and poorer classes; rather, these studies suggest that the money stays with the rich.
The article goes on to suggest that consolidation of wealth at the top does not lead to corporate expansion in terms of jobs and therefore boosting the economy; rather, the consolidation stays at the top and is fueled by bargaining for wages and for those top tier jobs, having specialized skills in global marketing. The studies also show that capital and inherited income is also playing an increasing role in the United States; again, money stays at the top and is passed on as if in aristocratic lineage or general nepotism.
All the studies give support to the argument that tax deductions for the rich, consolidated wealth among the rich (for various reasons stated), capital gains and inheritances, and earned income/capital income ratios all have lead to the current income inequality in the United States (rather than leading to boosting the economy as a whole - as the opposing arguments suppose). These conclusions are supported by comparisons with other countries in which the data supports these conclusions.