Chiral corrections to the scalar form factor in B_q to D_q transitions

TL;DR

This paper analyzes chiral loop corrections to the scalar form factor in B_q to D_q l nu decays, highlighting how these corrections influence the extraction of form factors and implications for new physics searches.

Contribution

It introduces a procedure to incorporate chiral corrections into lattice QCD calculations of B_q to D_q form factors, accounting for 1/m_Q suppressed operators and SU(3) breaking effects.

Findings

Chiral corrections tend to cancel with kinematic effects in B_s to D_s decays.

SU(3) flavor symmetry breaking corrections can reach up to 30%.

The results are crucial for precise new physics tests in semileptonic B decays.

Abstract

We consider chiral loop corrections to the scalar form factor in B_q to D_q l nu decays. First we consider chiral corrections to the 1/m_Q suppressed operators and then we propose the procedure for the extraction of the relevant form factor using lattice QCD results. In the case of B_s to D_s l nu decay we find that effects of kinematics and chiral corrections tend to cancel for the scalar form factor contributions. In particular the 1/m_Q suppression of chiral corrections is compensated by the SU(3) flavor symmetry breaking corrections which can be as large as 30%. The calculated corrections are relevant for the precise determination of possible new physics effects in B_q to D_q l nu decays.