By Saikat Chatterjee LONDON (Reuters) – Big speculative flows and not concerns about a worsening economic outlook explain the euro’s slide to a five-year low below $1.05 this week, a study by BNP Paribas showed. BNP Paribas strategists said the euro’s fall was driven primarily by large speculative flows with volumes centered around so-called “daily fixings” for currencies. This is an unusual development and suggests some investors could be taking out large positions on the direction of the single currency, which is down over 4.5% versus the dollar in April and set for its biggest monthly drop …