We present the results of the first lattice QCD study of the strong coupling g_{ D^* D pi}. From our simulations in the quenched approximation, we obtain g_{ D^* D pi} = 18.8 +/- 2.3^{ +1.1}_{ -2.0} and hat(g)_c = 0.67 +/- 0.08^{ +0.04}_{ -0.06}. Whereas previous theoretical studies gave different predictions, our result favours a large value for hat(g)_c. It agrees very well with the recent experimental value by CLEO. hat(g) varies very little with the heavy mass and we find in the infinite mass limit hat(g)_infinity = 0.69(18).
Categories: hep-ph hep-lat