Two coaches and almost three years since Arkansas last won a Southeastern Conference game, the Razorbacks took down the team that was the talk of college football last week. Feleipe Franks threw two touchdown passes and Arkansas intercepted K.J. Costello three times as the Razorbacks broke a 20-game SEC losing streak by upsetting No. 16 Mississippi State 21-14 on Saturday night. ''The mood in the locker room was probably everything you might expect,'' first-year Arkansas Sam Pittman said.