European Union antitrust regulators are asking British retailers whether the 3.8-billion-pound ($6.40 billion) merger of mobile phone retailer Carphone Warehouse and Dixons Retail will push up the prices of mobile phones and tablets. Carphone, Europes largest independent mobile phone retailer, and Europes No. 2 electrical products group, hope the merger will help them capitalize on the growing popularity of smartphones connected to consumer electronics such as ovens and fridges. The European Commission is now examining the deal and is scheduled to decide by June 25 whether to clear it, demand concessions or open a lengthy investigation.