Chiral loop corrections to weak decays of B mesons to positive and negative parity charmed mesons

We determine chiral loop corrections to the B meson decay amplitudes to positive and negative parity charmed mesons within a framework which combines heavy quark and chiral symmetries. Then we investigate the impact of the lowest-lying positive parity heavy mesons on the determination of the Isgur-Wise functions. The corrections due to these states are competitive with the contributions arising from K and eta meson loops. Since lattice studies rely on the chiral behavior of the amplitudes we discuss the chiral limit of our results. We find that the determination of the slope at zero recoil of the Isgur-Wise function xi for the B transition to negative parity charm mesons is moderately affected by the inclusion of new states, while the slope of tau_{1/2} is affected significantly more.