Suppose the payoff matrix shown is a stage game for an infinitely repeated game with a discount factor $\delta \in (0, 1)$.
Let $\sigma$ denote the trigger strategy. Find the range of $\delta$ that will make the strategy profile ($\sigma$, $\sigma$) a Nash Equilibrium of the repeated game.
Player 2
C D
Player 1
C (2, 2) (-1, 3)
D (3, -1) (0, 0)