$B to pi lbar{ u}$ Form Factors with NRQCD Heavy Quark and Clover Light Quark Actions

We report results on semileptonic $Btopi lbar{ u}$ decay form factors near $q^2_{rm max}$ using NRQCD heavy quark and clover light quark actions and currents improved through $O(alpha a)$. An inconsistency with the soft pion relation $f^0(q^2_{rm max})= f_B/f_{pi}$ found in a previous work is confirmed, and a possible solution with nonperturbative renormalization is discussed. We find that $f^+(q^2)$ is well described by the $B^*$ pole near $q^2_{rm max}$, and its $1/M_B$ scaling is also consistent with the prediction of the pole dominance model.