ORLANDO, Florida, Jan 26 (Reuters) - World stocks climbed to new highs and gold smashed through the $5,000-an-ounce barrier on Monday, while the dollar's slide gathered pace as investors braced for a deluge of U.S. earnings and a Federal Reserve policy decision this week. More on that below. In my ​column today I look into signs that the rumblings of a U.S. productivity boom may be going global. Could all that AI spending be ‌bearing fruit? It's early days, but investors and policymakers alike will be pay ...