German investment in the US is expected to rise by €39 billion because of lower US corporate taxes. German economists are warning that the changes sought by President Donald Trump mean that significant amounts of new investment and jobs will shift from Europe to the United States. “The tax competition will have a new dimension,” said Christoph Spengel, chairman of the corporate tax department at the University of Mannheim. Mr. Spengel, who is also a research associate at the Center for European Economic Research, and a group of tax experts at the university have done a detailed comparison of the...