Executives at the top carbonated soft drink firms are more positive on the future of the category in the US, but the decline of diet drinks shows no sign of abating, according to an analyst from Cowen and Company. In an analyst's note, Vivien Azer of equity research firm Cowen and Company said executives at Pepsico, Dr Pepper and Coke were becoming more confident of prospects in CSDs at Beverage Digest's recent conference.