Chiral loop corrections in B to D l nu decays

TL;DR

This paper calculates chiral loop corrections to B to D l nu decays, considering positive and negative parity charmed mesons, and discusses implications for lattice QCD and potential new physics effects.

Contribution

It introduces a combined heavy quark and chiral symmetry framework to evaluate loop corrections involving states of opposite parity in B to D decays.

Findings

Corrections from opposite parity states are comparable to K and eta meson loops.

Chiral behavior of amplitudes is analyzed in the chiral limit for lattice QCD relevance.

Comments on subleading form factors relevant for B_q to D_q tau nu decays.

Abstract

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. We find that corrections due to states of opposite parity 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 also comment on the extraction of 1/m_B, 1/m_D subleading form factors relevant for the studies of B_q to D_q tau nu decays, which are sensitive to possible helicity-suppressed new physics contributions.