Nonperturbative renormalization group approach to the Ising model: A derivative expansion at order ∂4

On the example of the three-dimensional Ising model, we show that nonperturbative renormalization group equations allow one to obtain very accurate critical exponents. Implementing the order ∂ 4 of the derivative expansion leads to v=0.632 and to an anomalous dimension η=0.033 which is significantly improved compared with lower orders calculations.